CVE-2022-26485: Mozilla Firefox Use-After-Free Vulnerability

High severity, CVSS 8.8. Actively exploited: in CISA KEV since 2022-03-07. EPSS: 14.3% chance of exploitation in the next 30 days.

Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0, Thunderbird < 91.6.2, and Focus < 97.3.0.

Affected products

• Mozilla Firefox: before 91.6.1 (fixed in 91.6.1); before 97.0.2 (fixed in 97.0.2)
• Mozilla Firefox Focus: before 97.3.0 (fixed in 97.3.0)
• Mozilla Firefox Mobile: before 97.3.0 (fixed in 97.3.0)
• Mozilla Thunderbird: before 91.6.2 (fixed in 91.6.2)

Published 2022-12-22. Last modified 2026-08-19.