CVE-2026-4699: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

Incorrect boundary conditions in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

Affected products

• Mozilla Firefox: before 115.34.0 (fixed in 115.34.0); before 149.0 (fixed in 149.0); from 128.0, before 140.9.0 (fixed in 140.9.0)

Published 2026-03-24. Last modified 2026-07-15.