Input validation error in Mozilla products - CVE-2026-109740
Published: October 16, 2026
Vulnerability identifier: #VU156025
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-109740
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to escape sandbox restrictions.
The vulnerability exists due to incorrect boundary validation in the Widget: Win32 component when handling widget operations. A remote attacker can trigger improperly handled boundary conditions to bypass sandbox restrictions.
Affected software
Firefox ESR
Mozilla Firefox
Firefox for Android
Mozilla Firefox
Firefox for Android
How to mitigate CVE-2026-109740
Install security update from vendor's website.
Firefox ESR - update to 153.5.0
Firefox for Android - update to 158.0
Mozilla Firefox - update to 158.0
Firefox for Android - update to 158.0
Mozilla Firefox - update to 158.0