CVE-2026-92035: Mozilla Firefox

Critical severity, CVSS 9.6. EPSS: 0.3% chance of exploitation in the next 30 days.

Sandbox escape due to incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Thunderbird 140.17, Firefox 156, Firefox ESR 153.3, Thunderbird 156, Thunderbird 153.3, Firefox ESR 115.42, and Firefox ESR 140.17.

Affected products

• Mozilla Firefox: before 115.42.0 (fixed in 115.42.0); from 116.0, before 140.17.0 (fixed in 140.17.0); from 141.0, before 153.3.0 (fixed in 153.3.0); from 154.0.0, before 156.0.0 (fixed in 156.0.0)
• Mozilla Thunderbird: before 140.17.0 (fixed in 140.17.0); from 141.0, before 153.3.0 (fixed in 153.3.0); from 154.0, before 156.0 (fixed in 156.0)

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