CVE-2026-12299: Mozilla Firefox · Type Confusion
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 5.4 Medium · patch available : update Mozilla Firefox when convenient.
Data as of 31 Oct 2026, 08:20 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 16 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
Mozilla has fixed this vulnerability in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. Users and administrators should update to these versions or later to remediate the issue. Patch status is confirmed by the vendor advisories. No additional mitigation steps are indicated beyond applying the official updates.
Description
JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2043139 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-57/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-58/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-59/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-60/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-61/ (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-12299 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2489212 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12299.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:38506 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36100 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:38751 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27733 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:30846 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27717 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33445 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36102 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:39428 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:37210 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:39141 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36103 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:39142 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36101 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:39706 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:39011 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:38753 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:37391 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:38750 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:27734 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:29940 (opens in a new tab)