CVE-2025-1012: Mozilla Firefox · Use After Free
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in 135 : patch Mozilla Firefox as a priority.
Data as of 26 Oct 2026, 09:15 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 135, 128.7, 115.20
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Feb 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 135, 128.7 or 115.20.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
Mozilla has released official fixes for this vulnerability in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135. Users and administrators should update to these versions or later to remediate the issue. Patch status is confirmed by the vendor advisory. No additional mitigation actions are required beyond applying the official updates.
Description
A race during concurrent delazification could have led to a use-after-free. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
References
- bugzilla.mozilla.org/show_bug.cgi?id=1939710 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-07/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-08/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-09/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-10/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-11/ (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/02/msg00006.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/02/msg00005.html (opens in a new tab)