Improper Interaction Between Multiple Correctly-Behaving Entities in Mozilla products - CVE-2026-109720
Published: October 16, 2026
Vulnerability identifier: #VU156016
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-2026-109720
CWE-ID: CWE-435
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to trigger incorrect execution of WebAssembly code that may compromise browser security.
The vulnerability exists due to incorrect just-in-time code generation in the JavaScript: WebAssembly component when compiling WebAssembly. A remote attacker can supply crafted WebAssembly that is miscompiled to produce execution behavior inconsistent with the intended program semantics.
Affected software
Firefox ESR
Mozilla Firefox
Firefox for Android
Debian Linux
firefox-esr (Debian package)
Mozilla Firefox
Firefox for Android
Debian Linux
firefox-esr (Debian package)
How to mitigate CVE-2026-109720
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-esr (Debian package) - update to 153.5.0esr-1~deb13u1
Firefox for Android - update to 158.0
Mozilla Firefox - update to 158.0
firefox-esr (Debian package) - update to 153.5.0esr-1~deb13u1