Protection mechanism failure in Mozilla products - CVE-2026-84129
Published: September 1, 2026
Vulnerability identifier: #VU146617
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-2026-84129
CWE-ID: CWE-693
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass site isolation restrictions.
The vulnerability exists due to improper isolation in the DOM: Navigation component when handling crafted web navigation. A remote attacker can trigger crafted navigation to bypass site isolation restrictions.
User interaction is required to visit a crafted website or URL.
Affected software
Firefox for Android
Mozilla Firefox
Firefox ESR
Mozilla Firefox
Firefox ESR
How to mitigate CVE-2026-84129
Install security update from vendor's website.
Firefox for Android - update to 155.0
Mozilla Firefox - update to 155.0
Firefox ESR - update to 153.2.0
Mozilla Firefox - update to 155.0
Firefox ESR - update to 153.2.0