CVE-2025-62800 describes a reflected cross-site scripting (XSS) vulnerability in FastMCP versions prior to 2.13.0, specifically within the OAuth client callback page (oauth_callback.py). This flaw allows unescaped user-controlled input to be embedded in HTML, leading to arbitrary JavaScript execution in the callback server's origin. With a CVSS score of 6.1 (Medium), this vulnerability is network-exploitable with low attack complexity, requiring user interaction, and could result in limited confidentiality and integrity impacts. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 2.13.0CPE matchmatch criteria | cpe:2.3:a:jlowin:fastmcp:*:*:*:*:*:*:*:* |
CVSS version used by this source: 4.0
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.
No media coverage found for this CVE.
The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.