XSS in Gohugoio Hugo
CVE-2026-100691
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/gohugoio/hugo/security/advisories/GHSA-q4xf-287f-98r8 (vendor-advisory)
- www.vulncheck.com/advisories/hugo-before-0.166.0-stored-xss-via-lineanchors-cod… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-100691?
- CVE-2026-100691 is a medium-severity vulnerability in Gohugoio Hugo, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-09-26.
- How severe is CVE-2026-100691?
- Medium severity. CVSS v3 base score is 5.4 out of 10.