CVE-2026-65697

MEDIUM 6.1

Fathom Lite 1.3.1 Stored XSS via /collect Endpoint

CVSS Score

6.1

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-79
Vendor	usefathom
Product	fathom
Published	Jul 23, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

usefathom / fathom

0 ≤ 1.3.1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/geo-chen/oss/blob/main/fathom.md vulncheck.com: https://www.vulncheck.com/advisories/fathom-lite-stored-xss-via-collect-endpoint

Credits

George Chen