Cross-Site Scripting (XSS) in loofah (CVE-2026-73490)
Summary
Cross-site scripting in loofah (CVE-2026-73490). Risk of unauthorized operations or information disclosure. Exploitable via href. Mitigation: upgrade to 2.25.2 or later.
Original description
The description as published by the source.
Summary
Loofah's HTML5 sanitizer restricted only the xlink:href attribute on certain SVG elements to local, same-document references. Browsers also accept a plain href attribute as an alternative to the deprecated xlink:href per the SVG 2 spec, but Loofah did not apply the same restriction to it, allowing those elements to reference arbitrary external documents.
Impact
SVG can load and render external SVG content by reference. If the referenced external SVG is same-origin and contains scripts or other dangerous content, it could execute in the context of the sanitized document. can load external images, which can be used for tracking. Modern browsers restrict cross-origin `` fetches, which limits but does not eliminate the risk.
Applications that sanitize user-supplied SVG (directly, or as part of HTML) with Loofah's default allowlist are affected.
Mitigation
Upgrade to Loofah >= 2.25.2.
Credit
Found by the maintainer, Mike Dalessio, during a security audit.
Source: GitHub Security Advisories (Global) 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-2026-73490 has been found in loofah.
Attackers can target a specific entry point like href over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.7/10.
What to do: upgrade loofah to 2.25.2 or later.
If unsure, ask your IT team or search "loofah CVE-2026-73490" on the vendor's site.
CVE-2026-73490 (loofah) — CWE-79 / CVSS v3 4.7
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: href
Patched: 2.25.2 — 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 loofah. Attackers reach the vulnerable code path via href without authentication.
Check the vendor advisory for the affected versions of loofah. Attack surface: href.
Severity: Medium (CVSS 4.7/10). Risk of unauthorized operations or information disclosure.
Update to 2.25.2.
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 'loofah' . 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
-
1Identify exposure identify
grep -r 'loofah' . | 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
loofah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 loofah to 2.25.2ステージング環境で 2.25.2 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。
-
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。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-73490 ruby-loofah
- Ubuntu UBUNTU-CVE-2026-73490 ruby-loofah