CVE-2026-16360: Mozilla Firefox

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

Memory safety bugs present in Firefox ESR 115.37, Firefox ESR 140.12 and Firefox 152. 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 153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Affected products

• Mozilla Firefox: before 115.38.0 (fixed in 115.38.0); before 153.0.0 (fixed in 153.0.0); from 128.1.0, before 140.13.0 (fixed in 140.13.0)
• Mozilla Thunderbird: before 140.13.0 (fixed in 140.13.0); from 141.0, before 153.0 (fixed in 153.0)

Published 2026-07-21. Last modified 2026-07-24.