{"cve":"CVE-2026-77250","nvd":{"published":"2026-09-22T18:17:17.720","modified":"2026-09-29T14:22:55.913","status":"Analyzed","description":"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-<client_id>.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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","score":6.1},"cwes":["CWE-312"],"references":["https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460","https://github.com/sooperset/mcp-atlassian/pull/1448","https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0","https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6","https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6"],"products":["mcp-atlassian:mcp_atlassian"],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-77250","score":0.00115,"percentile":0.01509,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-g5xv-mhgm-v5f6","url":"https://osv.dev/vulnerability/GHSA-g5xv-mhgm-v5f6","summary":"MCP Atlassian: OAuth fallback token storage writes plaintext access and refresh tokens with group-readable permissions","modified":"2026-10-01T17:56:14.889051764Z","packages":[{"ecosystem":"PyPI","name":"mcp-atlassian","purl":"pkg:pypi/mcp-atlassian","ranges":["<0.22.0"],"fixed":["0.22.0"]}]},{"id":"PYSEC-2026-4094","url":"https://osv.dev/vulnerability/PYSEC-2026-4094","summary":"MCP Atlassian: OAuth fallback token storage writes plaintext access and refresh tokens with group-readable permissions","modified":"2026-10-01T17:45:10.034044556Z","packages":[{"ecosystem":"PyPI","name":"mcp-atlassian","purl":"pkg:pypi/mcp-atlassian","ranges":["<0.22.0"],"fixed":["0.22.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}