Origin validation error in Mozilla products - CVE-2026-74960
Published: August 18, 2026
Vulnerability identifier: #VU144065
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-74960
CWE-ID: CWE-346
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass site isolation.
The vulnerability exists due to improper isolation enforcement in the WebExtensions component when handling extension-related web content. A remote attacker can cause the browser to process specially crafted web content to bypass site isolation.
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-2026-74960
Install security update from vendor's website.
Firefox ESR - addressed in versions 140.14.0, 153.1.0
Firefox for Android - update to 154.0
Mozilla Firefox - update to 154.0
Firefox for Android - update to 154.0
Mozilla Firefox - update to 154.0