CVE-2025-11711mediumCWE-591

CVE-2025-11711: medium-severity vulnerability in Mozilla Firefox

Some non-writable Object properties could be modified

Published 14 Oct 2025 · Updated 13 Apr 2026

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.5epss 0.2%

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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In the same product, most dangerous first.

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=1989978 https://lists.debian.org/debian-lts-announce/2025/10/msg00015.html https://lists.debian.org/debian-lts-announce/2025/10/msg00031.html https://www.mozilla.org/security/advisories/mfsa2025-81/https://www.mozilla.org/security/advisories/mfsa2025-82/https://www.mozilla.org/security/advisories/mfsa2025-83/https://www.mozilla.org/security/advisories/mfsa2025-84/https://www.mozilla.org/security/advisories/mfsa2025-85/