CVE-2026-0884: Mozilla Firefox · Use After Free
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical.
Data as of 26 Oct 2026, 14:05 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.
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 13 Jan 2026
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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
A fix is available and has been officially released by Mozilla. Users and administrators should update to Firefox 147 or Firefox ESR 140.7 (or later) to remediate this vulnerability. No additional mitigation steps are required beyond applying the official update.
Description
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2003588 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-01/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-03/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-04/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-05/ (opens in a new tab)