Use-after-free in Mozilla products - CVE-2026-84122
Published: September 1, 2026
Vulnerability identifier: #VU146611
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-2026-84122
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use-after-free in the Audio/Video component when processing crafted media content. A remote attacker can trigger a use-after-free condition to execute arbitrary code.
User interaction is required to visit a specially crafted website or URL.
Affected software
Firefox ESR
Mozilla Firefox
Firefox for Android
Mozilla Firefox
Firefox for Android
How to mitigate CVE-2026-84122
Install security update from vendor's website.
Firefox ESR - addressed in versions 140.15.0, 153.2.0
Firefox for Android - update to 155.0
Mozilla Firefox - update to 155.0
Firefox for Android - update to 155.0
Mozilla Firefox - update to 155.0