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Fencer Vulns
medium 5.4

CVE-2026-100691 json

Hugo before 0.166.0 Stored XSS via lineAnchors code block option

published 2026-09-26 43 d ago modified 2026-09-29 40 d ago also EUVD-2026-87664

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

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 `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.

Patch / fix

  • gohugoio hugo 0.166.0
  • hugo Debian 14 0.166.0-1

debian advisories DEBIAN-CVE-2026-100691

  • hugo hummingbird 1 0.166.0-0.1.hum1

red hat advisories RHSA-2026:66266

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-100691 updated cvss 5.4

github.com/gohugoio/hugo: Hugo: Stored cross-site scripting via unescaped lineAnchors option

  • Red Hat Enterprise Linux 10 grafana 12.4.3-2.el10 Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel8, openshift-gitops-1/argocd-rhel9 Red Hat OpenStack Platform 18.0 rhoso-operators/openstack-operator-bundle
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images hugo 0.166.0-0.1.hum1
    fixed: vendor fix RHSA-2026:66266
  • Red Hat Hardened Images grafana13.1 13.1.6-0.3.hum1, grafana13.2 13.2.1-0.6.hum1, grafana12.4 12.4.10-0.7.hum1
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
41 d ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • gohugoio hugo

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.