BREW-MCP-ATLASSIAN-CVE-2… (CVE-2026-27826)

Vulnerability from osv_homebrew – Published: 2026-08-13 17:13 – Updated: 2026-09-10 00:30 – Source website
VLAI
Summary
MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers
Details

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
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "upstream_fixed_in": "0.17.0"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "mcp-atlassian",
        "purl": "pkg:brew/mcp-atlassian"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.23.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "git",
    "upstream_evidence": [
      {
        "ecosystem": "GIT",
        "key": "https://github.com/sooperset/mcp-atlassian",
        "name": "https://github.com/sooperset/mcp-atlassian",
        "strategy": "git",
        "subject_version": "0.23.1"
      },
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/mcp-atlassian@0.23.1",
        "name": "mcp-atlassian",
        "strategy": "registry",
        "subject_version": "0.23.1"
      }
    ]
  },
  "details": "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.",
  "id": "BREW-mcp-atlassian-CVE-2026-27826",
  "modified": "2026-09-10T00:30:25Z",
  "published": "2026-08-13T17:13:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27826.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27826"
    },
    {
      "type": "FIX",
      "url": "https://github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291640e0528d9"
    }
  ],
  "schema_version": "1.7.3",
  "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",
  "upstream": [
    "CVE-2026-27826",
    "GHSA-7r34-79r5-rcc9",
    "PYSEC-2026-2621"
  ]
}



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