{"id":"CVE-2026-27826","aliases":["GHSA-7r34-79r5-rcc9","PYSEC-2026-2621"],"url":"https://o3.security/vulnerability/CVE-2026-27826","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.","published":"2026-03-10T18:46:12.069Z","modified":"2026-08-07T11:50:43.942151583Z","cvss":{"score":8.2,"severity":"HIGH","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"mcp-atlassian","fixedVersion":"0.17.0"}],"fix":{"url":"https://github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291640e0528d9","label":"sooperset/mcp-atlassian@5cd697d"},"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:50:43.942151583Z"}}