CVE-2019-9789: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 1.2% chance of exploitation in the next 30 days.

Mozilla developers and community members reported memory safety bugs present in Firefox 65. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox < 66.

Affected products

• Mozilla Firefox: before 66.0 (fixed in 66.0)

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