CVE-2026-2793: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Memory safety bugs present in Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird ESR 140.7, 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, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Affected products

• Mozilla Firefox: before 115.33.0 (fixed in 115.33.0); before 148.0 (fixed in 148.0); from 128.0, before 140.8.0 (fixed in 140.8.0)
• Mozilla Thunderbird: before 140.8.0 (fixed in 140.8.0); before 148.0 (fixed in 148.0)

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