CVE-2025-1012: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

A race during concurrent delazification could have led to a use-after-free. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

Affected products

• Mozilla Firefox: before 115.20.0 (fixed in 115.20.0); before 135.0 (fixed in 135.0); from 128.1.0, before 128.7.0 (fixed in 128.7.0)
• Mozilla Thunderbird: before 135.0 (fixed in 135.0); from 128.0.1, before 128.7.0 (fixed in 128.7.0)

Published 2025-02-04. Last modified 2026-10-05.