CVE-2019-9810: Mozilla Firefox

High severity, CVSS 8.8. EPSS: 29.7% chance of exploitation in the next 30 days.

Incorrect alias information in IonMonkey JIT compiler for Array.prototype.slice method may lead to missing bounds check and a buffer overflow. This vulnerability affects Firefox < 66.0.1, Firefox ESR < 60.6.1, and Thunderbird < 60.6.1.

Affected products

• Mozilla Firefox: before 60.6.1 (fixed in 60.6.1); before 66.0.1 (fixed in 66.0.1)
• Mozilla Thunderbird: before 60.6.1 (fixed in 60.6.1)
• Red Hat Enterprise Linux: version 8.0 only
• Red Hat Enterprise Linux Eus: version 8.1 only; version 8.2 only; version 8.4 only
• Red Hat Enterprise Linux Server Aus: version 8.2 only; version 8.4 only
• Red Hat Enterprise Linux Server Tus: version 8.2 only; version 8.4 only

Published 2019-04-26. Last modified 2026-06-17.