Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/LadybirdBrowser/ladybird/commit/c0d68bddf3e3616e5173835f0f4c1
- https://github.com/LadybirdBrowser/ladybird/security/advisories/GHSA-xj66-c4cw-x
FAQ
What is CVE-2026-119331?
CVE-2026-119331 is a vulnerability with a CVSS score of 7.1 (HIGH). Ladybird is a truly independent web browser. Prior to the c0d68bddf3e3616e5173835f0f4c155ee9700d91 commit, CSSStyleSheet.cssRules, insertRule(), and deleteRule() in Libraries/LibWeb/CSS/CSSStyleSheet....
How severe is CVE-2026-119331?
CVE-2026-119331 has been rated HIGH with a CVSS base score of 7.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-119331?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.