🛡️ CVE-2026-4692 — firefox

🔴 CVSS 10.0 — Critical ✅ No Known Exploit CWE-653 NVD
10.0
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2026-4692 is recorded against 2 packages.

  • firefox (from 128.0 up to 140.9.0)
  • thunderbird (fixed in 149.0)

Timeline and source

Published on 24 March 2026 and last revised on 15 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

bugzilla.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com

CVE-2026-4692 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity CRITICAL
CVSS Score 10.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CWE CWE-653
Public Exploit ✅ No
Source NVD
Published 2026-03-24
Updated 2026-08-11
Modified 2026-07-15
Fix URL N/A

Affected Packages

Software From version Fixed in
firefox 128.0 140.9.0
thunderbird 149.0

References

Similar Threats

Exploit Protection

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