{"id":"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.","aliases":["GHSA-mxxr-jv3v-6pgc"],"modified":"2026-03-14T12:44:32.616856Z","published":"2025-10-28T21:34:40.392Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62800.json","cwe_ids":["CWE-79"],"cna_assigner":"GitHub_M"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/jlowin/fastmcp","events":[{"introduced":"0"},{"fixed":"716e50dae0b445fb7fd0251725fc827c045d5fdd"}]}],"versions":["v0.1.0","v0.2.0","v0.3.0","v0.3.1","v0.3.2","v0.3.3","v0.3.4","v0.3.5","v0.4.0","v0.4.1","v1.0","v2.0.0","v2.1.0","v2.1.1","v2.1.2","v2.10.0","v2.10.1","v2.10.2","v2.10.3","v2.10.4","v2.10.5","v2.10.6","v2.11.0","v2.11.1","v2.11.2","v2.11.3","v2.12.0","v2.12.0rc1","v2.12.1","v2.12.2","v2.12.3","v2.12.4","v2.13.0rc1","v2.13.0rc2","v2.13.0rc3","v2.2.0","v2.2.1","v2.2.10","v2.2.2","v2.2.3","v2.2.4","v2.2.5","v2.2.6","v2.2.7","v2.2.8","v2.2.9","v2.3.0","v2.3.0-rc.1","v2.3.0-rc.2","v2.3.1","v2.3.2","v2.3.3","v2.3.4","v2.3.5","v2.4.0","v2.5.0","v2.5.1","v2.5.2","v2.6.0","v2.6.1","v2.7.0","v2.7.1","v2.8.0","v2.8.1","v2.9.0","v2.9.1","v2.9.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-62800.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"}]}