CVE-2026-73490 is a medium-severity (CVSS 4.7) Cross-site Scripting (XSS) vulnerability in loofah. O3 Security confirms whether CVE-2026-73490 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Loofah: SVG `href` attribute bypasses local-reference restriction
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73490.
Real-World Exposure
loofahReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. Prior to 2.25.2, Loofah's HTML5 sanitizer applies its local-reference restriction only to the xlink:href attribute on SVG use and feImage elements, while browsers also accept the plain href attribute. A crafted sanitized SVG can therefore reference an arbitrary same-origin external document; use may render external SVG content containing scripts or other dangerous content, and feImage may load external images for tracking. Applications that sanitize user-supplied SVG with Loofah's default allowlist are affected. This issue is fixed in version 2.25.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | loofah | all versions | 2.25.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for loofah. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update loofah to 2.25.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73490 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-73490 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-73490. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-73490 in your dependencies?
O3 detects CVE-2026-73490 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.