VULNERABILITY INTELLIGENCE

CVE-2025-62800

CVSS score6.1 MEDIUM
EPSS probability0.28%
CISA KEVNot currently listed
Published2025-10-28
Last modified2026-10-08
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Description

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.

Weakness classification

  • security-advisories@github.com: CWE-79

Primary references