CVE-2025-14321: Use-after-free in the WebRTC: Signaling component

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-12-09 · updated 2026-10-07
Weakness: CWE-416

Description

Use-after-free in the WebRTC: Signaling component. This vulnerability was fixed in Firefox 146, Firefox ESR 140.6, Thunderbird 146, and Thunderbird 140.6.

Affected products

Mozilla Firefox: before 140.6.0; before 146.0 — fixed in 140.6.0, 146.0
Mozilla Thunderbird: before 140.6.0; before 146.0 — fixed in 140.6.0, 146.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 140.6.0, 146.0; Mozilla Thunderbird 140.6.0, 146.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1992760
https://www.mozilla.org/security/advisories/mfsa2025-92/
https://www.mozilla.org/security/advisories/mfsa2025-94/
https://www.mozilla.org/security/advisories/mfsa2025-95/
https://www.mozilla.org/security/advisories/mfsa2025-96/

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