CVE-2026-119331

The Ladybird web browser is vulnerable to a Same-Origin Policy bypass due to missing origin-clean flag enforcement. Specifically, the CSSStyleSheet.cssRules, insertRule(), and deleteRule() functions in Libraries/LibWeb/CSS/CSSStyleSheet.cpp failed to trigger a SecurityError when handling cross-or...

CVE-2026-119331 Ladybird: Missing origin-clean enforcement in CSSStyleSheet allows cross-origin CSS read and mutation

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...