CVE-2026-4692: Sandbox Escape via Responsive Design Mode in Firefox <149
CVE-2026-4692 Published on March 24, 2026

Sandbox escape in the Responsive Design Mode component
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.

NVD

Vulnerability Analysis

CVE-2026-4692 is exploitable with network access, requires user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.

Attack Vector:

NETWORK

Attack Complexity:

HIGH

Privileges Required:

NONE

User Interaction:

REQUIRED

Scope:

UNCHANGED

Confidentiality Impact:

HIGH

Integrity Impact:

HIGH

Availability Impact:

HIGH

Weakness Type

What is a Separation of Privilege Vulnerability?

The product does not sufficiently compartmentalize functionality or processes that require different privilege levels, rights, or permissions. When a weakness occurs in functionality that is accessible by lower-privileged users, then without strong boundaries, an attack might extend the scope of the damage to higher-privileged users.

CVE-2026-4692 has been classified to as a Separation of Privilege vulnerability or weakness.

Products Associated with CVE-2026-4692

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-4692 are published in these products:

Mozilla Firefox

Mozilla FireFox Extended Support Release (ESR)

Mozilla Thunderbird

Red Hat Rhel Els

Red Hat Enterprise Linux Eus

Red Hat Enterprise Linux (RHEL)

Red Hat Rhel Aus

Red Hat Rhel Eus Long Life

Red Hat Rhel E4s

Red Hat Rhel Tus

Red Hat Rhel Eus

Affected Versions

Mozilla Firefox:

Version 115.34, <= 115.* is unaffected.
Version 140.9, <= 140.* is unaffected.
Version 149, <= * is unaffected.

Mozilla Thunderbird:

Version 140.9, <= 140.* is unaffected.
Version 149, <= * is unaffected.

Red Hat Enterprise Linux 10:

Version 0:140.9.0-1.el10_1 and below * is unaffected.

Red Hat Enterprise Linux 10:

Version 0:140.9.0-1.el10_1 and below * is unaffected.

Red Hat Enterprise Linux 10.0 Extended Update Support:

Version 0:140.9.0-1.el10_0 and below * is unaffected.

Red Hat Enterprise Linux 10.0 Extended Update Support:

Version 0:140.9.0-1.el10_0 and below * is unaffected.

Red Hat Enterprise Linux 7 Extended Lifecycle Support:

Version 0:140.9.0-1.el7_9 and below * is unaffected.

Red Hat Enterprise Linux 8:

Version 0:140.9.0-1.el8_10 and below * is unaffected.

Red Hat Enterprise Linux 8:

Version 0:140.9.0-1.el8_10 and below * is unaffected.

Red Hat Enterprise Linux 8.2 Advanced Update Support:

Version 0:140.9.0-1.el8_2 and below * is unaffected.

Red Hat Enterprise Linux 8.2 Advanced Update Support:

Version 0:140.9.0-1.el8_2 and below * is unaffected.

Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support:

Version 0:140.9.0-1.el8_4 and below * is unaffected.

Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support:

Version 0:140.9.0-1.el8_4 and below * is unaffected.

Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On:

Version 0:140.9.0-1.el8_4 and below * is unaffected.

Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On:

Version 0:140.9.0-1.el8_4 and below * is unaffected.

Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support:

Version 0:140.9.0-1.el8_6 and below * is unaffected.

Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support:

Version 0:140.9.0-1.el8_6 and below * is unaffected.

Red Hat Enterprise Linux 8.6 Telecommunications Update Service:

Version 0:140.9.0-1.el8_6 and below * is unaffected.

Red Hat Enterprise Linux 8.6 Telecommunications Update Service:

Version 0:140.9.0-1.el8_6 and below * is unaffected.

Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions:

Version 0:140.9.0-1.el8_6 and below * is unaffected.

Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions:

Version 0:140.9.0-1.el8_6 and below * is unaffected.

Red Hat Enterprise Linux 8.8 Telecommunications Update Service:

Version 0:140.9.0-1.el8_8 and below * is unaffected.

Red Hat Enterprise Linux 8.8 Telecommunications Update Service:

Version 0:140.9.0-1.el8_8 and below * is unaffected.

Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions:

Version 0:140.9.0-1.el8_8 and below * is unaffected.

Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions:

Version 0:140.9.0-1.el8_8 and below * is unaffected.

Red Hat Enterprise Linux 9:

Version 0:140.9.0-1.el9_7 and below * is unaffected.

Red Hat Enterprise Linux 9:

Version 0:140.9.0-1.el9_7 and below * is unaffected.

Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions:

Version 0:140.9.0-1.el9_0 and below * is unaffected.

Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions:

Version 0:140.9.0-1.el9_0 and below * is unaffected.

Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions:

Version 0:140.9.0-1.el9_2 and below * is unaffected.

Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions:

Version 0:140.9.0-1.el9_2 and below * is unaffected.

Red Hat Enterprise Linux 9.4 Extended Update Support:

Version 0:140.9.0-1.el9_4 and below * is unaffected.

Red Hat Enterprise Linux 9.4 Extended Update Support:

Version 0:140.9.0-1.el9_4 and below * is unaffected.

Red Hat Enterprise Linux 9.6 Extended Update Support:

Version 0:140.9.0-1.el9_6 and below * is unaffected.

Red Hat Enterprise Linux 9.6 Extended Update Support:

Version 0:140.9.0-1.el9_6 and below * is unaffected.

Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 7:

Exploit Probability

EPSS

0.49%

Percentile

39.16%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.

CVE-2026-4692: Sandbox Escape via Responsive Design Mode in Firefox <149CVE-2026-4692 Published on March 24, 2026

Vulnerability Analysis

Weakness Type

What is a Separation of Privilege Vulnerability?

Products Associated with CVE-2026-4692

Affected Versions

Exploit Probability

CVE-2026-4692: Sandbox Escape via Responsive Design Mode in Firefox <149
CVE-2026-4692 Published on March 24, 2026