CVE-2026-6746: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Affected products

• Mozilla Firefox: before 115.35.0 (fixed in 115.35.0); before 150.0 (fixed in 150.0); from 140.0, before 140.10.0 (fixed in 140.10.0)
• Mozilla Thunderbird: before 140.10.0 (fixed in 140.10.0)

Published 2026-04-21. Last modified 2026-07-15.