{"id":"CVE-2026-73497","summary":"MCP Atlassian is a Model Context Protocol (MCP): DNS-rebinding TOCTOU bypass of the SSRF fix (CVE-2026-27826): unauthenticated SSRF to cloud metadata","details":"MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). From 0.17.0 until 0.22.0, validate_url_for_ssrf resolves the attacker-controlled X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url header host once at middleware time, but the outbound request is built with the raw hostname and resolves it again at connection time with no IP pinning. An attacker-controlled DNS-rebinding name can return a public IP during validation and 169.254.169.254 or another internal IP during connection, enabling unauthenticated server-side requests to cloud metadata or internal services. The flaw spans src/mcp_atlassian/utils/urls.py, src/mcp_atlassian/servers/main.py, and src/mcp_atlassian/servers/dependencies.py; validate_url_for_ssrf returns only a verdict rather than a pinned IP, UserTokenMiddleware processes the attacker-controlled headers before fetcher creation, and the Jira and Confluence fetchers use the raw hostname. This issue is fixed in version 0.22.0.","aliases":["GHSA-489g-7rxv-6c8q"],"modified":"2026-09-18T11:47:01.365468936Z","published":"2026-09-14T19:50:23.241Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73497.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-918"]},"references":[{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73497.json"},{"type":"ADVISORY","url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-489g-7rxv-6c8q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73497"},{"type":"FIX","url":"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460"},{"type":"FIX","url":"https://github.com/sooperset/mcp-atlassian/pull/1448"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sooperset/mcp-atlassian","events":[{"introduced":"e191a2f2363b96d622599facafa3cf27ce2d3e44"},{"fixed":"b041733473f95119dd539542a43c280737a8e460"}],"database_specific":{"extracted_events":[{"introduced":"0.17.0"},{"fixed":"0.22.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v0.21.1","v0.21.0","v0.20.1","v0.20.0","v0.19.0","v0.18.1","v0.18.0","v0.17.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73497.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N"}]}