Description
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.
References (2)
Core 2
Core References
Exploit technical-description
exploit
Researcher Disclosure
https://github.com/geo-chen/oss/blob/main/fathom.md
Third Party Advisory third-party-advisory
https://www.vulncheck.com/advisories/fathom-lite-stored-xss-via-collect-endpoint
Scores
CVSS v3
6.1
EPSS
0.0016
EPSS Percentile
5.7%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-79
Status
published
Products (1)
usefathom/fathom
< 1.3.1
Published
Jul 23, 2026
Tracked Since
Jul 23, 2026