CVE-2026-100808: Mozilla Firefox

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

Mitigation bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.

Affected products

• Mozilla Firefox: before 153.4.0 (fixed in 153.4.0); from 154.0.0, before 157.0.0 (fixed in 157.0.0)
• Mozilla Thunderbird: before 153.4.0 (fixed in 153.4.0); from 154.0, before 157.0 (fixed in 157.0)

Published 2026-09-29. Last modified 2026-10-05.