CVE-2025-14321 Use-after-free in the WebRTC: Signaling component
A use-after-free flaw in WebRTC signaling allows attackers to execute arbitrary code, requiring users to upgrade Firefox and Thunderbird.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-14321?
CVE-2025-14321 is a critical use after free vulnerability in Mozilla Firefox, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-416
Which versions are affected by CVE-2025-14321?
It affects 2 products.
Products include Mozilla Firefox, Mozilla Thunderbird.
How do I fix CVE-2025-14321?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-14321 being exploited?
There is no known exploitation of CVE-2025-14321 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as DEBIAN-CVE-2025-14321, GHSA-g2fh-3663-3jf8, UBUNTU-CVE-2025-14321.