CVE-2026-4692: Mozilla Firefox · CWE-653
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 9.6 Critical · patch available : patch Mozilla Firefox as a priority.
Data as of 30 Oct 2026, 11:52 UTC
Contested
Critical score, yet low EPSS after six months- EPSS
- 0.5% chance of exploitation in 30 days – higher than 43% 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:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
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), GitHub proofs of concept, 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
This vulnerability is fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9. Users and administrators should upgrade to these versions or later to mitigate the risk. No additional mitigations are required beyond applying the official patches provided by Mozilla.
Description
Sandbox escape in the Responsive Design Mode component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2017643 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-20/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-21/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-22/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-23/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-24/ (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-4692 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2450748 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4692.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8427 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7843 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8315 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:5931 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:6342 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:5932 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:6917 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7840 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8285 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7858 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8850 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7842 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8289 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7838 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8288 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7839 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8286 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7841 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8287 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7845 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8290 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7837 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:8284 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:5930 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:6188 (opens in a new tab)