Cross-Site Scripting (XSS) in Hugo (CVE-2026-100691)
Summary
Cross-site scripting in Hugo (CVE-2026-100691). Risk of unauthorized operations or information disclosure. Exploitable via lineAnchors. Mitigation: upgrade to 0.166.0 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-100691 has been found in Hugo.
Attackers can target a specific entry point like lineAnchors over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade Hugo to 0.166.0 or later.
If unsure, ask your IT team or search "Hugo CVE-2026-100691" on the vendor's site.
CVE-2026-100691 (Hugo) — CWE-79 / CVSS v3 5.4
Attack vector: remote (network-reachable)
Attack surface: lineAnchors / href / highlight
Patched: 0.166.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in Hugo. Attackers reach the vulnerable code path via lineAnchors.
Check the vendor advisory for the affected versions of Hugo. Attack surface: lineAnchors / href / highlight.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 0.166.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Hugo' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'Hugo' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Hugoを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Hugo to 0.166.0ステージング環境で 0.166.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- web github.com
- web vulncheck.com
- web nvd.nist.gov
- web github.com