Input validation error in Mozilla products - CVE-2026-109733
Published: October 16, 2026
Vulnerability identifier: #VU155994
CSH Severity: High
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-109733
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disrupt correct JavaScript execution and potentially compromise browser security.
The vulnerability exists due to incorrect just-in-time compilation in the JavaScript Engine: JIT component when compiling JavaScript. A remote attacker can supply crafted JavaScript that triggers miscompilation to produce incorrect execution behavior that may undermine browser security.
Affected software
Mozilla Firefox
Firefox ESR
Firefox for Android
Debian Linux
firefox-esr (Debian package)
Firefox ESR
Firefox for Android
Debian Linux
firefox-esr (Debian package)
How to mitigate CVE-2026-109733
Install security update from vendor's website.
Mozilla Firefox - update to 158.0
Firefox for Android - update to 158.0
Firefox ESR - addressed in versions 115.43.0, 153.5.0
firefox-esr (Debian package) - update to 153.5.0esr-1~deb13u1
Firefox for Android - update to 158.0
Firefox ESR - addressed in versions 115.43.0, 153.5.0
firefox-esr (Debian package) - update to 153.5.0esr-1~deb13u1