XSS in Usefathom Fathom

CVE-2026-65697

Fathom Lite through 1.3.1 contains a stored cross-site scripting vulnerability in the analytics collection endpoint that allows unauthenticated attackers to inject a javascript: URI into the Top Pages dashboard by supplying a crafted hostname and pathname to the unauthenticated /collect endpoint. The parseHostname and parsePathname functions perform no URI scheme validation, allowing a javascript: hostname combined with a newline-prefixed pathname to be stored and later rendered as an anchor href in the authenticated dashboard without sanitization, enabling session hijacking and full account takeover when an operator clicks the poisoned entry.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.003 (19.4th percentile) — read the EPSS interpretation.