CVE-2019-9795: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 1.7% chance of exploitation in the next 30 days.

A vulnerability where type-confusion in the IonMonkey just-in-time (JIT) compiler could potentially be used by malicious JavaScript to trigger a potentially exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Affected products

• Mozilla Firefox: before 66.0 (fixed in 66.0)
• Mozilla Firefox ESR: before 60.6 (fixed in 60.6)
• Mozilla Thunderbird: before 60.6 (fixed in 60.6)

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