CVE-2026-74934

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 154 Firefox ESR versions prior to 115.39 Firefox ESR versions prior to 140.14 Firefox ESR versions prior to 153.1 Thunderbird versions prior to 154 Thunderbird versions prior to 140.14 Thunderbird versions prior to 153.1

Description A site isolation issue exists within the Graphics: CanvasWebGL component. Site isolation is a security mechanism that ensures web pages from different sites are processed in separate processes to prevent one site from accessing data from another.

Recommendations Update Firefox to version 154 or later. Update Firefox ESR to version 115.39 or later. Update Firefox ESR to version 140.14 or later. Update Firefox ESR to version 153.1 or later. Update Thunderbird to version 154 or later. Update Thunderbird to version 140.14 or later. Update Thunderbird to version 153.1 or later.