CVE-2025-1937: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

Memory safety bugs present in Firefox 135, Thunderbird 135, Firefox ESR 115.20, Firefox ESR 128.7, and Thunderbird 128.7. 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 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Affected products

• Mozilla Firefox: before 115.21.0 (fixed in 115.21.0); before 128.8.0 (fixed in 128.8.0); before 135.0 (fixed in 135.0)
• Mozilla Thunderbird: before 128.8.0 (fixed in 128.8.0); from 129.0, before 136.0 (fixed in 136.0)

Published 2025-03-04. Last modified 2026-10-05.