CVE-2021-38498: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 1.5% chance of exploitation in the next 30 days.

During process shutdown, a document could have caused a use-after-free of a languages service object, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2.

Affected products

• Mozilla Firefox: before 93.0 (fixed in 93.0)
• Mozilla Firefox ESR: before 91.2 (fixed in 91.2)
• Mozilla Thunderbird: before 91.2 (fixed in 91.2)

Published 2021-11-03. Last modified 2026-06-17.