CVE-2025-1931: Mozilla Firefox · Use After Free
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 7.5 High : upgrade to 136 soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 136
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Mar 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade Mozilla Firefox to 136.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
Mozilla has released official fixes for this vulnerability in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8. Users and administrators should update to these versions or later to remediate the issue. Since the vulnerability is fixed in these releases, no additional mitigation steps are required beyond applying the official patches.
Description
It was possible to cause a use-after-free in the content process side of a WebTransport connection, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.
References
- bugzilla.mozilla.org/show_bug.cgi?id=1944126 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-14/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-15/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-16/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-17/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-18/ (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00006.html (opens in a new tab)