{"id":"CVE-2026-77246","state":"PUBLISHED","title":"MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path","description":"MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0.","publishedAt":"2026-09-22T18:51:54.540Z","updatedAt":"2026-09-24T15:26:33.550Z","severity":{"score":7.4,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["sooperset mcp-atlassian"],"affected":[{"vendor":"sooperset","product":"mcp-atlassian","versions":[{"version":"< 0.22.0","status":"affected"}]}],"references":["https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j","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-22","CWE-200","CWE-441"],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/77xxx/CVE-2026-77246.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77246","state":"PUBLISHED","datePublished":"2026-09-22T18:51:54.540Z","dateUpdated":"2026-09-24T15:26:33.550Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-20T19:02:23.416Z"},"containers":{"cna":{"title":"MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path","descriptions":[{"lang":"en","value":"MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0."}],"affected":[{"vendor":"sooperset","product":"mcp-atlassian","versions":[{"version":"< 0.22.0","status":"affected"}]}],"references":[{"url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j","name":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j","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":"LOW","attackVector":"ADJACENT_NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-22","lang":"en","description":"CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-200","lang":"en","description":"CWE-200: Exposure of Sensitive Information to an Unauthorized Actor","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-441","lang":"en","description":"CWE-441: Unintended Proxy or Intermediary ('Confused Deputy')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-22T18:51:54.540Z"},"source":{"advisory":"GHSA-wv8v-v4c5-v75j","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-24T15:26:25.494462Z","id":"CVE-2026-77246","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-24T15:26:33.550Z"}}]}}}