CVE-2026-119331 Ladybird: Missing origin-clean enforcement in CSSStyleSheet allows cross-origin CSS read and mutation
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-119331?
CVE-2026-119331 is a high-severity vulnerability in LadybirdBrowser ladybird, published on 30 Oct 2026.
Official description
Ladybird is a truly independent web browser. Prior to the c0d68bddf3e3616e5173835f0f4c155ee9700d91 commit, CSSStyleSheet.cssRules, insertRule(), and deleteRule() in Libraries/LibWeb/CSS/CSSStyleSheet.cpp did not enforce the stylesheet origin-clean flag with the required SecurityError, even though cross-origin imported stylesheets were correctly marked non-origin-clean. A malicious page could read parsed rules from a stylesheet loaded without CORS and could insert or delete rules in the victim stylesheet, bypassing the Same-Origin Policy. Reading could expose selectors, generated content, feature markers, or other sensitive rule text, while mutation could alter page visibility or layout. The issue does not provide memory corruption, code execution, or persistence after the attacker page closes. This vulnerability is fixed by commit c0d68bddf3e3616e5173835f0f4c155ee9700d91.
Which versions are affected by CVE-2026-119331?
How do I fix CVE-2026-119331?
No fix has been published for CVE-2026-119331 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-119331 being exploited?
There is no known exploitation of CVE-2026-119331 in the wild and no public exploit code.
Sources
Also known as GHSA-xj66-c4cw-xwh3.