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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-119331
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-30 20:17:07 UTC
Updated2026-10-30 23:17:09 UTC
DescriptionLadybird 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Problem Types: CWE-200 | CWE-346 | CWE-200 CWE-200: Exposure of Sensitive Information to an Unauthorized Actor | CWE-346 CWE-346: Origin Validation Error

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA LadybirdBrowser Ladybird affected < c0d68bddf3e3616e5173835f0f4c155ee9700d91 Not specified

References

ReferenceSourceLinkTags
github.com/LadybirdBrowser/ladybird/security/advisories/GHSA-xj66-c4cw-xwh3 [email protected] github.com
github.com/LadybirdBrowser/ladybird/commit/c0d68bddf3e3616e5173835f0f4c1... [email protected] github.com
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