CVE-2021-38496: Debian Linux

High severity, CVSS 8.8. EPSS: 1.7% chance of exploitation in the next 30 days.

During operations on MessageTasks, a task may have been removed while it was still scheduled, resulting in memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.15, Thunderbird < 91.2, Firefox ESR < 91.2, Firefox ESR < 78.15, and Firefox < 93.

Affected products

• Debian Debian Linux: version 9.0 only; version 10.0 only; version 11.0 only
• Mozilla Firefox: before 93.0 (fixed in 93.0); from 91.0, before 91.2 (fixed in 91.2)
• Mozilla Firefox ESR: before 78.15 (fixed in 78.15)
• Mozilla Thunderbird: before 78.15 (fixed in 78.15); from 91.0, before 91.2 (fixed in 91.2)

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