Bug 2541895 (CVE-2026-100691)

Summary: CVE-2026-100691 github.com/gohugoio/hugo: Hugo: Stored cross-site scripting via unescaped lineAnchors option
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anjoseph, eglynn, jjoyce, jprabhak, jpretori, jschluet, lchilton, lhh, mburns, mgarciac, rhel-process-autobot, sfeifer, watson-tool-maintainers, wtam
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Hugo. The syntax highlighter fails to properly sanitize the lineAnchors option, resulting in a stored Cross-Site Scripting (XSS) vulnerability. A remote attacker capable of submitting Markdown content can exploit this by supplying a crafted lineAnchors code block attribute. When the site is generated and published, this flaw allows arbitrary script execution in the browsers of users visiting the affected pages.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-26 13:41:04 UTC 
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.