CVE-2026-16406 is a mitigation bypass vulnerability located in the Networking component of Mozilla Firefox. This flaw allows an attacker to circumvent security mitigations, potentially enabling unauthorized network-related actions. The vulnerability affects all Firefox versions before 153 and was resolved in Firefox 153. The CVSS 3.1 base score is 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N), indicating it is remotely exploitable without privileges or user interaction and results in high confidentiality and integrity impact. The official Mozilla advisory (MFSA 2026-68) lists this vulnerability among multiple high-impact fixes in Firefox 153. No active exploitation has been observed.

Successful exploitation of this vulnerability could allow remote attackers to bypass mitigation controls in the Firefox Networking component, leading to high impact on confidentiality and integrity of user data. The vulnerability does not affect availability. Because it requires no privileges or user interaction, it poses a significant risk if unpatched. However, no known exploits in the wild have been reported.

Mozilla has released an official fix for this vulnerability in Firefox version 153. Users and administrators should update affected Firefox installations to version 153 or later to remediate this issue. Since this is not a cloud service, remediation depends on applying the vendor-supplied update. There are no vendor advisories indicating any temporary or alternative mitigations; applying the official update is required.