CVE-2025-11711: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.2% chance of exploitation in the next 30 days.

There was a way to change the value of JavaScript Object properties that were supposed to be non-writeable. This vulnerability was fixed in Firefox 144, Firefox ESR 115.29, Firefox ESR 140.4, Thunderbird 144, and Thunderbird 140.4.

Affected products

• Mozilla Firefox: before 115.29.0 (fixed in 115.29.0); before 144.0 (fixed in 144.0); from 116.0, before 140.4.0 (fixed in 140.4.0)
• Mozilla Thunderbird: before 140.4.0 (fixed in 140.4.0); from 141.0, before 144.0 (fixed in 144.0)

Published 2025-10-14. Last modified 2026-06-17.