{"id":"CVE-2026-77250","summary":"MCP Atlassian: OAuth fallback token storage writes plaintext access and refresh tokens with group-readable permissions","details":"MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, OAuthConfig writes a plaintext fallback file containing access and refresh tokens under the user's .mcp-atlassian directory using process-default permissions. On systems with a permissive umask, same-group or other local users and processes can read the persisted tokens and reuse the associated Atlassian access. The advisory traces the vulnerable input and processing flow through OAuthConfig._save_tokens, ~/.mcp-atlassian/oauth-\u003cclient_id\u003e.json, access_token, and refresh_token, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.","aliases":["GHSA-g5xv-mhgm-v5f6"],"modified":"2026-09-23T03:47:21.691798857Z","published":"2026-09-22T17:51:02.674Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-312"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77250.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77250.json"},{"type":"FIX","url":"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460"},{"type":"FIX","url":"https://github.com/sooperset/mcp-atlassian/pull/1448"},{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"},{"type":"ADVISORY","url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77250"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sooperset/mcp-atlassian","events":[{"introduced":"0"},{"fixed":"b041733473f95119dd539542a43c280737a8e460"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"0.22.0"}],"source":"AFFECTED_FIELD"}}],"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","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/osv-test-cve-osv-conversion/osv-output/CVE-2026-77250.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N"}]}