Vulnerability Description
Hugo versions 0.75.0 through 0.165.x contain a stored cross-site scripting vulnerability: the syntax highlighter does not escape the `lineAnchors` option before passing it to Chroma, which writes the value verbatim into the `id` and `href` attributes of the generated line-number markup. A crafted `lineAnchors` value supplied as a Markdown code fence attribute (or passed to the `highlight` template function) results in unescaped HTML in the rendered page, allowing arbitrary JavaScript to execute in the browsers of visitors to the generated site. This affects sites that build and publish Markdown from untrusted contributors; Hugo's security model otherwise considers content trusted input. Fixed in 0.166.0, where the `lineAnchors` value is HTML-escaped before being passed to Chroma.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Gohugo | Hugo | >= 0.75.0, < 0.166.0 |
Related Weaknesses (CWE)
References
- https://github.com/gohugoio/hugo/security/advisories/GHSA-q4xf-287f-98r8Vendor Advisory
- https://www.vulncheck.com/advisories/hugo-before-0.166.0-stored-xss-via-lineanchThird Party Advisory
FAQ
What is CVE-2026-100691?
CVE-2026-100691 is a vulnerability with a CVSS score of 5.4 (MEDIUM). Hugo versions 0.75.0 through 0.165.x contain a stored cross-site scripting vulnerability: the syntax highlighter does not escape the `lineAnchors` option before passing it to Chroma, which writes the ...
How severe is CVE-2026-100691?
CVE-2026-100691 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-100691?
Check the references section above for vendor advisories and patch information. Affected products include: Gohugo Hugo.