Use-after-free in Mozilla products - CVE-2026-117921
Published: October 27, 2026
Vulnerability identifier: #VU158106
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-117921
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to potentially cause a denial of service.
The vulnerability exists due to use-after-free in the CSS parsing and computation component when processing styles. A remote attacker can supply crafted style content to trigger access to freed memory and potentially crash the browser.
Affected software
Mozilla Firefox
Firefox ESR
Firefox for Android
Firefox ESR
Firefox for Android
How to mitigate CVE-2026-117921
Install security update from vendor's website.
Mozilla Firefox - update to 159.0
Firefox for Android - update to 159.0
Firefox ESR - addressed in versions 115.44.0, 153.6.0
Firefox for Android - update to 159.0
Firefox ESR - addressed in versions 115.44.0, 153.6.0