{"id":"CVE-2025-62800","aliases":["GHSA-mxxr-jv3v-6pgc","PYSEC-2026-1364"],"url":"https://o3.security/vulnerability/CVE-2025-62800","summary":"FastMCP vulnerable to reflected XSS in client's callback page","details":"FastMCP is the standard framework for building MCP applications. Versions prior to 2.13.0 have a reflected cross-site scripting vulnerability in the OAuth client callback page (oauth_callback.py) where unescaped user-controlled values are inserted into the generated HTML, allowing arbitrary JavaScript execution in the callback server origin. The issue is fixed in version 2.13.0.","published":"2025-10-28T21:34:40.392Z","modified":"2026-07-15T01:49:14.957096844Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"fastmcp","fixedVersion":"2.13.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62800.json"},{"type":"ADVISORY","url":"https://github.com/jlowin/fastmcp/security/advisories/GHSA-mxxr-jv3v-6pgc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-62800"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-15T01:49:14.957096844Z"}}