CVE-2026-2807: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 0.5% chance of exploitation in the next 30 days.

Memory safety bugs present in Firefox 147 and Thunderbird 147. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 148 and Thunderbird 148.

Affected products

• Mozilla Firefox: before 148.0 (fixed in 148.0)
• Mozilla Thunderbird: before 148.0 (fixed in 148.0)

Published 2026-02-24. Last modified 2026-07-15.