CVE-2026-16383 is a mitigation bypass vulnerability affecting the DOM: Networking component in Mozilla Firefox. This issue allows bypassing security mitigations designed to protect the browser's networking internals. The vulnerability was fixed in Firefox 153 and Firefox ESR 140.13. The CVSS v3.1 score is 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating that it can be exploited remotely without privileges or user interaction, resulting in high impact on confidentiality, integrity, and availability. The vendor advisory confirms the fix and lists this vulnerability among multiple high-impact security issues resolved in the same releases.

Successful exploitation of this vulnerability could allow an attacker to bypass mitigation controls in the DOM networking component, potentially leading to full compromise of confidentiality, integrity, and availability of the affected Firefox browser. The CVSS score of 9.8 reflects critical severity with network attack vector and no required privileges or user interaction. However, there are no known active exploits in the wild at the time of the advisory.

Mozilla has released official fixes for this vulnerability in Firefox 153 and Firefox ESR 140.13. Users and administrators should update affected Firefox installations to these versions or later to remediate the issue. Since this is not a cloud service, patching the client software is required. There is no indication from the vendor advisory that any additional mitigation or workarounds are necessary beyond applying the update.