{"id":"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.","aliases":["GHSA-7r34-79r5-rcc9","PYSEC-2026-2621"],"modified":"2026-07-15T01:48:51.504774856Z","published":"2026-03-10T18:46:12.069Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-918"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27826.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sooperset/mcp-atlassian","events":[{"introduced":"0"},{"fixed":"e191a2f2363b96d622599facafa3cf27ce2d3e44"},{"fixed":"5cd697dfce9116ef330b8dc7a91291640e0528d9"}],"database_specific":{"source":["CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:sooperset:mcp_atlassian:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"0.17.0"}]}}],"versions":["v0.16.1","v0.16.0","v0.15.0","v0.14.3","v0.14.2","v0.14.1","v0.14.0","v0.13.1","v0.13.0","v0.12.0","v0.11.12","v0.11.11","v0.11.10","v0.11.9","v0.11.8","v0.11.7","v0.11.6","v0.11.5","v0.11.4","v0.11.3","v0.11.2","v0.11.1","v0.11.0","v0.10.6","v0.10.5","v0.10.4","v0.10.3","v0.10.2","v0.10.1","v0.10.0","v0.9.0","v0.8.4","v0.8.3","v0.8.2","v0.8.1","v0.8.0","v0.7.1","v0.7.0","v0.6.5","v0.6.4","v0.6.3","v0.6.2","v0.6.1","v0.6.0","v0.5.0","v0.4.0","v0.3.1","v0.3.0","v0.2.6","v0.2.5","v0.2.4","v0.2.3","v0.2.2","v0.2.1","v0.2.0","v0.1.16","v0.1.15","v0.1.14","v0.1.13","v0.1.12","v0.1.11","v0.1.10","v0.1.8","v0.1.7","v0.1.6","v0.1.5","v0.1.4"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27826.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N"}]}