Use-after-free in Mozilla Firefox and Firefox for Android - CVE-2026-124871
Published: November 10, 2026
Vulnerability identifier: #VU164571
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-2026-124871
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service and potentially execute arbitrary code.
The vulnerability exists due to use-after-free in Firefox's DOM: HTML Parser component when parsing HTML content. A remote attacker can supply crafted HTML to trigger access to freed memory, potentially causing a crash or arbitrary code execution.
Affected software
Mozilla Firefox
Firefox for Android
Firefox for Android
How to mitigate CVE-2026-124871
Install security update from vendor's website.
Mozilla Firefox - update to 160.0
Firefox for Android - update to 160.0
Firefox for Android - update to 160.0