{"id":"CVE-2026-73497","state":"PUBLISHED","title":"MCP Atlassian is a Model Context Protocol (MCP): DNS-rebinding TOCTOU bypass of the SSRF fix (CVE-2026-27826): unauthenticated SSRF to cloud metadata","description":"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.","publishedAt":"2026-09-14T19:50:23.241Z","updatedAt":"2026-09-15T13:56:00.939Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["sooperset mcp-atlassian"],"affected":[{"vendor":"sooperset","product":"mcp-atlassian","versions":[{"version":">= 0.17.0, < 0.22.0","status":"affected"}]}],"references":["https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-489g-7rxv-6c8q","https://github.com/sooperset/mcp-atlassian/pull/1448","https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460","https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/73xxx/CVE-2026-73497.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-73497","state":"PUBLISHED","datePublished":"2026-09-14T19:50:23.241Z","dateUpdated":"2026-09-15T13:56:00.939Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-12T19:00:33.736Z"},"containers":{"cna":{"title":"MCP Atlassian is a Model Context Protocol (MCP): DNS-rebinding TOCTOU bypass of the SSRF fix (CVE-2026-27826): unauthenticated SSRF to cloud metadata","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"sooperset","product":"mcp-atlassian","versions":[{"version":">= 0.17.0, < 0.22.0","status":"affected"}]}],"references":[{"url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-489g-7rxv-6c8q","name":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-489g-7rxv-6c8q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/sooperset/mcp-atlassian/pull/1448","name":"https://github.com/sooperset/mcp-atlassian/pull/1448","tags":["x_refsource_MISC"]},{"url":"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460","name":"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460","tags":["x_refsource_MISC"]},{"url":"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0","name":"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-14T19:50:23.241Z"},"source":{"advisory":"GHSA-489g-7rxv-6c8q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-15T13:25:24.644811Z","id":"CVE-2026-73497","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-15T13:56:00.939Z"}}]}}}