CVE-2026-65697 fathom vulnerability
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.
Browse Cross-site Scripting security risksQuick answer
usefathom fathom should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- <= 1.3.1
Fixed versions
- Apply the latest vendor-supported patched version.
How to fix it
CVE-2026-65697 affects fathom and involves cross-site scripting. Successful exploitation may run attacker-controlled script in a trusted user's browser and expose session or application data. Treat this as a high-priority fix, especially when the affected component or endpoint is reachable by untrusted users. No confirmed fixed version is recorded for CVE-2026-65697; follow the linked vendor advisory, apply its mitigation, and update fathom as soon as a supported patched release is available.
- Inventory every deployment, device, package, plugin, container, build, and environment that uses fathom.
- Compare the installed version with the recorded affected range: <= 1.3.1.
- No confirmed fixed version is recorded for CVE-2026-65697; follow the linked vendor advisory, apply its mitigation, and update fathom as soon as a supported patched release is available.
- Until patched, reduce public exposure, disable the affected workflow where practical, and allow access only from trusted users and systems.
- Review configuration, roles, tokens, network paths, and exposed endpoints connected to fathom; remove access that is not required.
- Review submissions, stored content, administrator activity, CSP reports, and web logs for script payloads or suspicious browser requests.
- If exploitation is suspected, isolate affected assets, preserve evidence, rotate exposed credentials or keys, restore trusted data, and rebuild compromised systems before returning them to service.
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Verify the fix
- Confirm every affected asset now runs the fixed vendor-supported release or has the documented mitigation for CVE-2026-65697 in place.
- Use a safe regression test to confirm the affected cross-site scripting path no longer produces the vulnerable behavior.
- Confirm temporary access controls, endpoint restrictions, network blocks, and least-privilege settings remain effective after the update.
- Review post-remediation logs and rerun Fixnx plus the relevant package, dependency, firmware, browser, or product-specific security check.
- Document affected assets, versions, changes, validation evidence, reviewed logs, and any credential rotation, cleanup, or replacement completed.
Related categories
Related security risks
More published guidance from the same primary category.
Trusted references
FAQ
What is affected by CVE-2026-65697?
usefathom fathom versions listed as affected should be reviewed: <= 1.3.1.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.