CVE-2026-92066: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Sandbox escape in the Profile Backup component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.

Affected products

• Mozilla Firefox: before 156.0.0 (fixed in 156.0.0)
• Mozilla Thunderbird: before 156.0 (fixed in 156.0)

Published 2026-09-15. Last modified 2026-10-05.