Main Vulnerability Database Vulnerabilities #VU146629

Improper access control in Mozilla Firefox and Firefox for Android - CVE-2026-84128

Published: September 1, 2026

Vulnerability identifier: #VU146629

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-84128

CWE-ID: CWE-284

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to escalate privileges.

The vulnerability exists due to improper access control in the WebDriver BiDi component when handling protocol functionality. A remote user can perform crafted protocol actions to escalate privileges.

Affected software

Mozilla Firefox
Firefox for Android

How to mitigate CVE-2026-84128

Install security update from vendor's website.

Mozilla Firefox - update to 155.0
Firefox for Android - update to 155.0

External References

Related Security Bulletins