CVE-2026-16365: Mozilla Firefox

High severity, CVSS 8.8. EPSS: 0.3% chance of exploitation in the next 30 days.

Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, Firefox ESR 140.15, and Thunderbird 140.15.

Affected products

• Mozilla Firefox: before 153.0.0 (fixed in 153.0.0)
• Mozilla Thunderbird: before 153.0 (fixed in 153.0)

Published 2026-07-21. Last modified 2026-09-01.