CVE-2026-100821

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 157 Firefox ESR versions prior to 115.42 Firefox ESR versions prior to 140.17 Firefox ESR versions prior to 153.4 Thunderbird versions prior to 157

Description A site isolation issue exists within the Panning and Zooming 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 157 or later. Update Firefox ESR to version 115.42 or later. Update Firefox ESR to version 140.17 or later. Update Firefox ESR to version 153.4 or later. Update Thunderbird to version 157 or later.