CVE-2026-16390 in Firefox
Summary
by MITRE • 07/21/2026
Mitigation bypass in the Enterprise Policies component. This vulnerability was fixed in Firefox 153 and Firefox ESR 140.13.
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Analysis
by VulDB Data Team • 07/21/2026
This vulnerability represents a significant security flaw within the Enterprise Policies component of Mozilla Firefox browsers, specifically targeting the mitigation controls designed to protect against various exploitation techniques. The issue allows attackers to bypass critical security measures that are typically enforced through enterprise policy configurations, effectively undermining the intended protection mechanisms for organizations relying on Firefox for their browser security. This type of vulnerability is particularly concerning in enterprise environments where strict security policies are implemented to prevent unauthorized access and maintain system integrity.
The technical nature of this flaw suggests an implementation weakness within Firefox's enterprise policy handling subsystem that permits unauthorized modification or circumvention of security controls. According to CWE classification systems, this vulnerability likely falls under categories related to policy enforcement failures or privilege escalation mechanisms within browser security frameworks. The flaw enables adversaries to potentially override security restrictions that would normally prevent certain actions or access patterns, creating opportunities for malicious activities that should have been blocked by the enterprise configuration policies.
The operational impact of this vulnerability extends beyond simple browser functionality issues, as it affects the fundamental security posture of organizations relying on Firefox Enterprise Policies for their protection. Attackers could exploit this bypass to gain elevated privileges or access restricted resources within the browser environment, potentially leading to data exfiltration, privilege escalation, or further exploitation of the compromised system. This vulnerability directly impacts the trust model that enterprise users place in their security configurations, undermining the effectiveness of administrative controls that are meant to enforce secure browsing practices across organizational networks.
Organizations using affected Firefox versions should immediately implement the available patches released in Firefox 153 and Firefox ESR 140.13, as these updates contain the necessary fixes for the enterprise policy bypass issue. Security teams should conduct thorough assessments of their current browser configurations to identify any potential exploitation attempts that may have occurred during the vulnerability window. The remediation process should include verification of enterprise policies to ensure proper enforcement after patching, and organizations should consider implementing additional monitoring controls to detect anomalous behavior patterns that might indicate attempted exploitation of this vulnerability type.
This vulnerability aligns with attack patterns described in the MITRE ATT&CK framework under techniques related to privilege escalation and defense evasion, where attackers leverage weaknesses in application security controls to bypass protective measures. The fix addresses fundamental issues in Firefox's policy enforcement mechanism, which are critical for maintaining secure browser operations in enterprise environments. Security professionals should recognize this as a high-severity issue requiring immediate attention due to its potential to undermine organizational security postures and enable more sophisticated attacks against enterprise networks.