Vulnerability-Lookup

PYSEC-2026-4257

Vulnerability from pysec - Published: 2026-10-15 10:22 - Updated: 2026-10-15 14:38

Details

Summary

PraisonAI's MCP HTTP-stream server authenticates requests only when an API key is configured; the CLI defaults --api-key to None, so praisonai mcp serve --transport http-stream exposes the full MCP surface unauthenticated. A request with no Authorization (and no Origin) can initialize and tools/list (~50 tools), and the dispatcher forwards tool-call arguments to handlers without validating them against the advertised inputSchema. Runtime-confirmed for unauthenticated initialize/tools/list and the dispatcher schema-bypass. This is not an RCE/file-read in 4.6.63 — workflow.run/workflow.run_file are runtime-refuted (adapter regression). Severity Medium–High.

Details

Affected component

Package: praisonai 4.6.63. Files: src/praisonai/praisonai/mcp_server/transports/http_stream.py, mcp_server/cli.py, mcp_server/server.py (dispatcher).

Vulnerable code / root cause

Path: src/praisonai/praisonai/mcp_server/transports/http_stream.py

Function: mcp_post / _validate_origin

Snippet:

if self.api_key:                       # auth applied ONLY when api_key is set
    auth_header = request.headers.get("Authorization", "")
    if not auth_header.startswith("Bearer ") or auth_header[7:] != self.api_key:
        return JSONResponse({"error": "Unauthorized"}, status_code=401)
# _validate_origin: returns True when the Origin header is absent

Issue: with api_key=None, no auth check runs; a missing Origin header is allowed, so non-browser clients (curl/Burp) are not blocked.

Path: src/praisonai/praisonai/mcp_server/cli.py

Function: cmd_serve (argparse)

Snippet:

parser.add_argument("--api-key", default=None)   # unauthenticated by default

Path: src/praisonai/praisonai/mcp_server/server.py

Function: _handle_tools_call

Snippet:

result = await tool.handler(**arguments)   # arguments forwarded without inputSchema validation

Issue: attacker-controlled arguments are passed straight to the handler; the dispatcher does not validate them against the tool's advertised inputSchema. The only thing rejecting undeclared keys is the handler's own Python signature.

Attack flow

Operator runs praisonai mcp serve --transport http-stream (no --api-key).
Attacker (no auth, no Origin) sends initialize → session; tools/list → enumerates ~50 tools; tools/call → arguments pass through unvalidated.

Why existing protection is bypassed

Auth is opt-in (only added when an api key is set); missing Origin is allowed; the dispatcher does not enforce inputSchema.

Security boundary

Unauthenticated access to the MCP tool surface. Default bind 127.0.0.1 (any local process / multi-user host; remote only if --host 0.0.0.0).

Scope limits (do not overclaim)

praisonai.workflow.run / workflow.run_file are runtime-refuted in 4.6.63: the adapter calls AgentsGenerator(...) missing the required config_list argument → errors before any execution/file open. Several other tool adapters also error at runtime. No unauthenticated RCE/arbitrary-file-open via these tools at HEAD.
MCP knowledge.add file read is broken (see FT-01_Knowledge_FileRead_Negative_Report.md).

Proof of Concept

Environment

Real MCP HTTP-stream server (api_key=None) in a local runtime (127.0.0.1:18090). Runnable assets: PraisonAI-Runtime-Repro\runtime-files\ (docker-compose.mcp.yml). MCP requests use Accept: application/json + header Mcp-Session-Id.

Steps to reproduce

MCP-Initialize: POST /mcp initialize (no Authorization) → 200 + mcp-session-id.
MCP-Tools-List-NoAuth: POST /mcp tools/list with that session id → 200 + ~50 tools.
MCP-Schema-Bypass: tools/call with an undeclared extra argument (__undeclared_evil_param__).

Expected result

The transport requires authentication; the dispatcher validates arguments against inputSchema.

Actual result

initialize/tools/list succeed with no auth and no Origin header.
The undeclared argument reaches the handler (got an unexpected keyword argument '__undeclared_evil_param__'), proving no schema validation at the dispatcher.

Screenshots

03-MCP-Schema-Bypass 02-MCP-Tools-List-NoAuth

Screenshots

Unauthenticated MCP initialize

A POST request to /mcp with method initialize succeeds without an Authorization header. The server returns HTTP 200 OK, exposes MCP capabilities, and issues an mcp-session-id to the unauthenticated client.

01-MCP-Initialize-NoAuth

Unauthenticated MCP tools/list

After initialization, the same unauthenticated MCP session can call tools/list using only the issued Mcp-Session-Id. The server returns HTTP 200 OK and exposes tool names, schemas, and annotations.

02-MCP-Tools-List-NoAuth

MCP tool-call schema bypass

The unauthenticated MCP client calls tools/call with an extra argument not declared in the tool schema. Instead of rejecting the schema-violating input at the dispatcher layer, the unexpected parameter reaches the Python handler and causes an unexpected keyword argument error. This confirms incomplete input-schema enforcement for tool calls.

03-MCP-Schema-Bypass

Impact

Unauthenticated tool enumeration and tool-call surface; LLM-key/cost abuse and data access via whichever tools function (impact currently limited by several broken adapters and the default loopback bind). No confirmed unauthenticated RCE/file-read in 4.6.63.

Severity

7.3 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Impacted products

Name	purl
praisonai	pkg:pypi/praisonai

Aliases

JSON

To clipboard

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        "ecosystem": "PyPI",
        "name": "praisonai",
        "purl": "pkg:pypi/praisonai"
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      "ranges": [
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          "events": [
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      ]
    }
  ],
  "aliases": [
    "CVE-2026-61427",
    "GHSA-hc5v-gxvj-58wh"
  ],
  "details": "## Summary\n\nPraisonAI\u0027s MCP HTTP-stream server authenticates requests only when an API key is configured; the CLI defaults `--api-key` to `None`, so `praisonai mcp serve --transport http-stream` exposes the full MCP surface unauthenticated. A request with no `Authorization` (and no `Origin`) can `initialize` and `tools/list` (~50 tools), and the dispatcher forwards tool-call arguments to handlers without validating them against the advertised `inputSchema`. Runtime-confirmed for unauthenticated `initialize`/`tools/list` and the dispatcher schema-bypass. This is **not** an RCE/file-read in 4.6.63 \u2014 `workflow.run`/`workflow.run_file` are runtime-refuted (adapter regression). Severity Medium\u2013High.\n\n## Details\n\n### Affected component\n- Package: `praisonai` 4.6.63. Files: `src/praisonai/praisonai/mcp_server/transports/http_stream.py`, `mcp_server/cli.py`, `mcp_server/server.py` (dispatcher).\n\n### Vulnerable code / root cause\n\nPath:\n`src/praisonai/praisonai/mcp_server/transports/http_stream.py`\n\nFunction:\n`mcp_post` / `_validate_origin`\n\nSnippet:\n```python\nif self.api_key:                       # auth applied ONLY when api_key is set\n    auth_header = request.headers.get(\"Authorization\", \"\")\n    if not auth_header.startswith(\"Bearer \") or auth_header[7:] != self.api_key:\n        return JSONResponse({\"error\": \"Unauthorized\"}, status_code=401)\n# _validate_origin: returns True when the Origin header is absent\n```\nIssue: with `api_key=None`, no auth check runs; a missing `Origin` header is allowed, so non-browser clients (curl/Burp) are not blocked.\n\nPath:\n`src/praisonai/praisonai/mcp_server/cli.py`\n\nFunction:\n`cmd_serve` (argparse)\n\nSnippet:\n```python\nparser.add_argument(\"--api-key\", default=None)   # unauthenticated by default\n```\n\nPath:\n`src/praisonai/praisonai/mcp_server/server.py`\n\nFunction:\n`_handle_tools_call`\n\nSnippet:\n```python\nresult = await tool.handler(**arguments)   # arguments forwarded without inputSchema validation\n```\nIssue: attacker-controlled `arguments` are passed straight to the handler; the dispatcher does not validate them against the tool\u0027s advertised `inputSchema`. The only thing rejecting undeclared keys is the handler\u0027s own Python signature.\n\n### Attack flow\n1. Operator runs `praisonai mcp serve --transport http-stream` (no `--api-key`).\n2. Attacker (no auth, no Origin) sends `initialize` \u2192 session; `tools/list` \u2192 enumerates ~50 tools; `tools/call` \u2192 arguments pass through unvalidated.\n\n### Why existing protection is bypassed\nAuth is opt-in (only added when an api key is set); missing `Origin` is allowed; the dispatcher does not enforce `inputSchema`.\n\n### Security boundary\nUnauthenticated access to the MCP tool surface. Default bind `127.0.0.1` (any local process / multi-user host; remote only if `--host 0.0.0.0`).\n\n### Scope limits (do not overclaim)\n- `praisonai.workflow.run` / `workflow.run_file` are **runtime-refuted in 4.6.63**: the adapter calls `AgentsGenerator(...)` missing the required `config_list` argument \u2192 errors before any execution/file open. Several other tool adapters also error at runtime. No unauthenticated RCE/arbitrary-file-open via these tools at HEAD.\n- MCP `knowledge.add` file read is broken (see `FT-01_Knowledge_FileRead_Negative_Report.md`).\n\n## Proof of Concept\n\n### Environment\nReal MCP HTTP-stream server (`api_key=None`) in a local runtime (`127.0.0.1:18090`). Runnable assets: `PraisonAI-Runtime-Repro\\runtime-files\\` (`docker-compose.mcp.yml`). MCP requests use `Accept: application/json` + header `Mcp-Session-Id`.\n\n### Steps to reproduce\n1. `MCP-Initialize`: `POST /mcp` initialize (no Authorization) \u2192 `200` + `mcp-session-id`.\n2. `MCP-Tools-List-NoAuth`: `POST /mcp` `tools/list` with that session id \u2192 `200` + ~50 tools.\n3. `MCP-Schema-Bypass`: `tools/call` with an undeclared extra argument (`__undeclared_evil_param__`).\n\n### Expected result\nThe transport requires authentication; the dispatcher validates arguments against `inputSchema`.\n\n### Actual result\n- `initialize`/`tools/list` succeed with no auth and no Origin header.\n- The undeclared argument reaches the handler (`got an unexpected keyword argument \u0027__undeclared_evil_param__\u0027`), proving no schema validation at the dispatcher.\n\n### Screenshots\n\u003cimg width=\"1544\" height=\"798\" alt=\"03-MCP-Schema-Bypass\" src=\"https://github.com/user-attachments/assets/5a4cb764-9428-487d-b4e0-2854cbda7fb7\" /\u003e\n\u003cimg width=\"1538\" height=\"793\" alt=\"02-MCP-Tools-List-NoAuth\" src=\"https://github.com/user-attachments/assets/6356af71-867f-4fbc-a994-c7ca338fd2aa\" /\u003e\n\n### Screenshots\n\n**Unauthenticated MCP initialize**\n\nA POST request to `/mcp` with method `initialize` succeeds without an `Authorization` header. The server returns HTTP 200 OK, exposes MCP capabilities, and issues an `mcp-session-id` to the unauthenticated client.\n\n\u003cimg width=\"1546\" height=\"804\" alt=\"01-MCP-Initialize-NoAuth\" src=\"https://github.com/user-attachments/assets/2a62ee6b-99d3-4a38-a752-bfe6165c8c04\" /\u003e\n\n**Unauthenticated MCP tools/list**\n\nAfter initialization, the same unauthenticated MCP session can call `tools/list` using only the issued `Mcp-Session-Id`. The server returns HTTP 200 OK and exposes tool names, schemas, and annotations.\n\n\u003cimg width=\"1538\" height=\"793\" alt=\"02-MCP-Tools-List-NoAuth\" src=\"https://github.com/user-attachments/assets/f55189ff-13aa-4c36-a617-3d2ee4a52a84\" /\u003e\n\n**MCP tool-call schema bypass**\n\nThe unauthenticated MCP client calls `tools/call` with an extra argument not declared in the tool schema. Instead of rejecting the schema-violating input at the dispatcher layer, the unexpected parameter reaches the Python handler and causes an `unexpected keyword argument` error. This confirms incomplete input-schema enforcement for tool calls.\n\n\u003cimg width=\"1544\" height=\"798\" alt=\"03-MCP-Schema-Bypass\" src=\"https://github.com/user-attachments/assets/d3f36e50-2363-4eb2-8b3c-985ff0e27f6e\" /\u003e\n\n## Impact\nUnauthenticated tool enumeration and tool-call surface; LLM-key/cost abuse and data access via whichever tools function (impact currently limited by several broken adapters and the default loopback bind). No confirmed unauthenticated RCE/file-read in 4.6.63.",
  "id": "PYSEC-2026-4257",
  "modified": "2026-10-15T14:38:02.299001Z",
  "published": "2026-10-15T10:22:53.407530Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-hc5v-gxvj-58wh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61427"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62178"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/MervinPraison/PraisonAI"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/praisonai-before-authentication-bypass-via-http-stream"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/praisonai"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-hc5v-gxvj-58wh"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "PraisonAI: MCP HTTP-stream transport is unauthenticated by default, exposing tool enumeration and an unvalidated tool-call surface"
}

CVE-2026-61427 (GCVE-0-2026-61427)

Vulnerability from cvelistv5 – Published: 2026-07-15 11:25 – Updated: 2026-07-16 15:18

Title

PraisonAI before 4.6.78 Authentication Bypass via HTTP-stream

Summary

PraisonAI before 4.6.78 exposes the MCP HTTP-stream transport without authentication by default: the CLI --api-key option defaults to None, and the server only enforces Authorization/Bearer checks when an API key is configured. When an operator runs 'praisonai mcp serve --transport http-stream' without an API key, an unauthenticated client (no Authorization header, and no Origin header, which is also permitted) can initialize a session, enumerate the available tools (tools/list), and invoke tools (tools/call). Additionally, the dispatcher forwards tool-call arguments to handlers without validating them against the advertised inputSchema. The server binds to 127.0.0.1 by default, so remote exploitation requires the operator to bind to a network-accessible address (e.g., --host 0.0.0.0).

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

7.3 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-16 15:17 UTC

CWE

CWE-20 - Improper Input Validation

Assigner

VulnCheck CNA under the mitre root

CNA scorecard B 84/100 over 6503 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/MervinPraison/PraisonAI/securi…	vendor-advisory
https://www.vulncheck.com/advisories/praisonai-be…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
MervinPraison	PraisonAI	Affected: 0 , < 4.6.78 (semver) Unaffected: 4.6.78 (semver) cpe:2.3:a:praison:praisonai::::::::

Date Public

2026-06-25 00:00

Credits

dinhvaren

Show details on NVD website

JSON

To clipboard

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GHSA-HC5V-GXVJ-58WH

Vulnerability from github – Published: 2026-10-08 21:58 – Updated: 2026-10-08 21:58

Summary

PraisonAI: MCP HTTP-stream transport is unauthenticated by default, exposing tool enumeration and an unvalidated tool-call surface

Details

Summary

Details

Affected component

Package: praisonai 4.6.63. Files: src/praisonai/praisonai/mcp_server/transports/http_stream.py, mcp_server/cli.py, mcp_server/server.py (dispatcher).

Vulnerable code / root cause

Path: src/praisonai/praisonai/mcp_server/transports/http_stream.py

Function: mcp_post / _validate_origin

Snippet:

if self.api_key:                       # auth applied ONLY when api_key is set
    auth_header = request.headers.get("Authorization", "")
    if not auth_header.startswith("Bearer ") or auth_header[7:] != self.api_key:
        return JSONResponse({"error": "Unauthorized"}, status_code=401)
# _validate_origin: returns True when the Origin header is absent

Issue: with api_key=None, no auth check runs; a missing Origin header is allowed, so non-browser clients (curl/Burp) are not blocked.

Path: src/praisonai/praisonai/mcp_server/cli.py

Function: cmd_serve (argparse)

Snippet:

parser.add_argument("--api-key", default=None)   # unauthenticated by default

Path: src/praisonai/praisonai/mcp_server/server.py

Function: _handle_tools_call

Snippet:

result = await tool.handler(**arguments)   # arguments forwarded without inputSchema validation

Attack flow

Operator runs praisonai mcp serve --transport http-stream (no --api-key).
Attacker (no auth, no Origin) sends initialize → session; tools/list → enumerates ~50 tools; tools/call → arguments pass through unvalidated.

Why existing protection is bypassed

Auth is opt-in (only added when an api key is set); missing Origin is allowed; the dispatcher does not enforce inputSchema.

Security boundary

Unauthenticated access to the MCP tool surface. Default bind 127.0.0.1 (any local process / multi-user host; remote only if --host 0.0.0.0).

Scope limits (do not overclaim)

praisonai.workflow.run / workflow.run_file are runtime-refuted in 4.6.63: the adapter calls AgentsGenerator(...) missing the required config_list argument → errors before any execution/file open. Several other tool adapters also error at runtime. No unauthenticated RCE/arbitrary-file-open via these tools at HEAD.
MCP knowledge.add file read is broken (see FT-01_Knowledge_FileRead_Negative_Report.md).

Proof of Concept

Environment

Steps to reproduce

MCP-Initialize: POST /mcp initialize (no Authorization) → 200 + mcp-session-id.
MCP-Tools-List-NoAuth: POST /mcp tools/list with that session id → 200 + ~50 tools.
MCP-Schema-Bypass: tools/call with an undeclared extra argument (__undeclared_evil_param__).

Expected result

The transport requires authentication; the dispatcher validates arguments against inputSchema.

Actual result

initialize/tools/list succeed with no auth and no Origin header.
The undeclared argument reaches the handler (got an unexpected keyword argument '__undeclared_evil_param__'), proving no schema validation at the dispatcher.

Screenshots

03-MCP-Schema-Bypass 02-MCP-Tools-List-NoAuth

Screenshots

Unauthenticated MCP initialize

01-MCP-Initialize-NoAuth

Unauthenticated MCP tools/list

02-MCP-Tools-List-NoAuth

MCP tool-call schema bypass

03-MCP-Schema-Bypass

Impact

Severity

7.3 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.6.77"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "praisonai"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.6.78"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-61427"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-306",
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-08T21:58:42Z",
    "nvd_published_at": "2026-07-15T17:16:52Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nPraisonAI\u0027s MCP HTTP-stream server authenticates requests only when an API key is configured; the CLI defaults `--api-key` to `None`, so `praisonai mcp serve --transport http-stream` exposes the full MCP surface unauthenticated. A request with no `Authorization` (and no `Origin`) can `initialize` and `tools/list` (~50 tools), and the dispatcher forwards tool-call arguments to handlers without validating them against the advertised `inputSchema`. Runtime-confirmed for unauthenticated `initialize`/`tools/list` and the dispatcher schema-bypass. This is **not** an RCE/file-read in 4.6.63 \u2014 `workflow.run`/`workflow.run_file` are runtime-refuted (adapter regression). Severity Medium\u2013High.\n\n## Details\n\n### Affected component\n- Package: `praisonai` 4.6.63. Files: `src/praisonai/praisonai/mcp_server/transports/http_stream.py`, `mcp_server/cli.py`, `mcp_server/server.py` (dispatcher).\n\n### Vulnerable code / root cause\n\nPath:\n`src/praisonai/praisonai/mcp_server/transports/http_stream.py`\n\nFunction:\n`mcp_post` / `_validate_origin`\n\nSnippet:\n```python\nif self.api_key:                       # auth applied ONLY when api_key is set\n    auth_header = request.headers.get(\"Authorization\", \"\")\n    if not auth_header.startswith(\"Bearer \") or auth_header[7:] != self.api_key:\n        return JSONResponse({\"error\": \"Unauthorized\"}, status_code=401)\n# _validate_origin: returns True when the Origin header is absent\n```\nIssue: with `api_key=None`, no auth check runs; a missing `Origin` header is allowed, so non-browser clients (curl/Burp) are not blocked.\n\nPath:\n`src/praisonai/praisonai/mcp_server/cli.py`\n\nFunction:\n`cmd_serve` (argparse)\n\nSnippet:\n```python\nparser.add_argument(\"--api-key\", default=None)   # unauthenticated by default\n```\n\nPath:\n`src/praisonai/praisonai/mcp_server/server.py`\n\nFunction:\n`_handle_tools_call`\n\nSnippet:\n```python\nresult = await tool.handler(**arguments)   # arguments forwarded without inputSchema validation\n```\nIssue: attacker-controlled `arguments` are passed straight to the handler; the dispatcher does not validate them against the tool\u0027s advertised `inputSchema`. The only thing rejecting undeclared keys is the handler\u0027s own Python signature.\n\n### Attack flow\n1. Operator runs `praisonai mcp serve --transport http-stream` (no `--api-key`).\n2. Attacker (no auth, no Origin) sends `initialize` \u2192 session; `tools/list` \u2192 enumerates ~50 tools; `tools/call` \u2192 arguments pass through unvalidated.\n\n### Why existing protection is bypassed\nAuth is opt-in (only added when an api key is set); missing `Origin` is allowed; the dispatcher does not enforce `inputSchema`.\n\n### Security boundary\nUnauthenticated access to the MCP tool surface. Default bind `127.0.0.1` (any local process / multi-user host; remote only if `--host 0.0.0.0`).\n\n### Scope limits (do not overclaim)\n- `praisonai.workflow.run` / `workflow.run_file` are **runtime-refuted in 4.6.63**: the adapter calls `AgentsGenerator(...)` missing the required `config_list` argument \u2192 errors before any execution/file open. Several other tool adapters also error at runtime. No unauthenticated RCE/arbitrary-file-open via these tools at HEAD.\n- MCP `knowledge.add` file read is broken (see `FT-01_Knowledge_FileRead_Negative_Report.md`).\n\n## Proof of Concept\n\n### Environment\nReal MCP HTTP-stream server (`api_key=None`) in a local runtime (`127.0.0.1:18090`). Runnable assets: `PraisonAI-Runtime-Repro\\runtime-files\\` (`docker-compose.mcp.yml`). MCP requests use `Accept: application/json` + header `Mcp-Session-Id`.\n\n### Steps to reproduce\n1. `MCP-Initialize`: `POST /mcp` initialize (no Authorization) \u2192 `200` + `mcp-session-id`.\n2. `MCP-Tools-List-NoAuth`: `POST /mcp` `tools/list` with that session id \u2192 `200` + ~50 tools.\n3. `MCP-Schema-Bypass`: `tools/call` with an undeclared extra argument (`__undeclared_evil_param__`).\n\n### Expected result\nThe transport requires authentication; the dispatcher validates arguments against `inputSchema`.\n\n### Actual result\n- `initialize`/`tools/list` succeed with no auth and no Origin header.\n- The undeclared argument reaches the handler (`got an unexpected keyword argument \u0027__undeclared_evil_param__\u0027`), proving no schema validation at the dispatcher.\n\n### Screenshots\n\u003cimg width=\"1544\" height=\"798\" alt=\"03-MCP-Schema-Bypass\" src=\"https://github.com/user-attachments/assets/5a4cb764-9428-487d-b4e0-2854cbda7fb7\" /\u003e\n\u003cimg width=\"1538\" height=\"793\" alt=\"02-MCP-Tools-List-NoAuth\" src=\"https://github.com/user-attachments/assets/6356af71-867f-4fbc-a994-c7ca338fd2aa\" /\u003e\n\n### Screenshots\n\n**Unauthenticated MCP initialize**\n\nA POST request to `/mcp` with method `initialize` succeeds without an `Authorization` header. The server returns HTTP 200 OK, exposes MCP capabilities, and issues an `mcp-session-id` to the unauthenticated client.\n\n\u003cimg width=\"1546\" height=\"804\" alt=\"01-MCP-Initialize-NoAuth\" src=\"https://github.com/user-attachments/assets/2a62ee6b-99d3-4a38-a752-bfe6165c8c04\" /\u003e\n\n**Unauthenticated MCP tools/list**\n\nAfter initialization, the same unauthenticated MCP session can call `tools/list` using only the issued `Mcp-Session-Id`. The server returns HTTP 200 OK and exposes tool names, schemas, and annotations.\n\n\u003cimg width=\"1538\" height=\"793\" alt=\"02-MCP-Tools-List-NoAuth\" src=\"https://github.com/user-attachments/assets/f55189ff-13aa-4c36-a617-3d2ee4a52a84\" /\u003e\n\n**MCP tool-call schema bypass**\n\nThe unauthenticated MCP client calls `tools/call` with an extra argument not declared in the tool schema. Instead of rejecting the schema-violating input at the dispatcher layer, the unexpected parameter reaches the Python handler and causes an `unexpected keyword argument` error. This confirms incomplete input-schema enforcement for tool calls.\n\n\u003cimg width=\"1544\" height=\"798\" alt=\"03-MCP-Schema-Bypass\" src=\"https://github.com/user-attachments/assets/d3f36e50-2363-4eb2-8b3c-985ff0e27f6e\" /\u003e\n\n## Impact\nUnauthenticated tool enumeration and tool-call surface; LLM-key/cost abuse and data access via whichever tools function (impact currently limited by several broken adapters and the default loopback bind). No confirmed unauthenticated RCE/file-read in 4.6.63.",
  "id": "GHSA-hc5v-gxvj-58wh",
  "modified": "2026-10-08T21:58:42Z",
  "published": "2026-10-08T21:58:42Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-hc5v-gxvj-58wh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61427"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62178"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/MervinPraison/PraisonAI"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/praisonai-before-authentication-bypass-via-http-stream"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "PraisonAI: MCP HTTP-stream transport is unauthenticated by default, exposing tool enumeration and an unvalidated tool-call surface"
}

Sightings

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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PYSEC-2026-4257

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CVE-2026-61427 (GCVE-0-2026-61427)

GHSA-HC5V-GXVJ-58WH

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