---
id: CVE-2026-100691
title: >-
  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
  `hre…
summary: >-
  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
  `hre…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: gohugoio
product: hugo
affected:
  - hugo >= 0.75.0 < 0.166.0
published: '2026-09-26'
updated: '2026-09-26'
sourceUpdated: '2026-09-26T14:16:53.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100691'
references:
  - url: 'https://github.com/gohugoio/hugo/security/advisories/GHSA-q4xf-287f-98r8'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/hugo-before-0.166.0-stored-xss-via-lineanchors-code-block-option
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-26T13:33:20.905Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.