Out-of-bounds read in Firefox ESR - CVE-2026-8946
Published: May 19, 2026
Vulnerability identifier: #VU131833
CSH Severity: High
CVSS v4.0: 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/E:U/U:Amber
CVE-ID: CVE-2026-8946
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Mozilla
Affected software:
Firefox ESR
Firefox ESR
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to incorrect boundary conditions in the Audio/Video: Web Codecs component when processing crafted web content. A remote attacker can cause the browser to process specially crafted content to execute arbitrary code.
User interaction is required to visit a specially crafted website or URL.
How to mitigate CVE-2026-8946
Install security update from vendor's website.