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CVE-2026-119331: Ladybird browser lets other sites read and change its CSS

CVE-2026-119331 · published 5 days ago

Summary

The Ladybird web browser could let a malicious website view and alter the styling rules of another site's page, even when the page’s CSS was loaded from a different origin. This could expose hidden design details or allow the attacker to change how the page looks. Updating Ladybird to the latest version resolves the issue.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software

Vendor	Product	Affected versions
ladybirdbrowser	ladybird	< c0d68bddf3e3616e5173835f0f4c155ee9700d91

Original advisory text

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 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.

References

https://github.com/LadybirdBrowser/ladybird/commit/c0d68bddf3e3616e5173835f0f4c1... Patch
https://github.com/LadybirdBrowser/ladybird/security/advisories/GHSA-xj66-c4cw-x... Vendor Advisory
https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/119xxx/CVE-2026-1193... Vendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-119331 Vendor Advisory

Fix within

Internet-facing 60 days

Internal At next upgrade

Not known to be exploited
Needs hands-on effort to exploit
Gives an attacker partial control

Severity

7.1 High

Exploitation

<1% chance of attack within 30 days

Type

CWE-200Information Exposure

CWE-346Origin Validation Error

Timeline

Published30 Oct 2026

Updated4 Nov 2026

First seen30 Oct 2026

Sources

CVE-2026-119331 · NVD

CVE-2026-119331 · MITRE

CVE-2026-119331 · OSV

GHSA-xj66-c4cw-xwh3 · GHSA

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