CVE-2026-16366 in Firefox
Summary
by MITRE • 07/21/2026
Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153.
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Analysis
by VulDB Data Team • 07/21/2026
This privilege escalation vulnerability exists within the Document Object Model navigation component of Firefox browser implementation, representing a critical security flaw that allows unauthorized elevation of privileges through malicious DOM manipulation. The vulnerability stems from insufficient access controls and validation mechanisms within the browser's DOM navigation handling system, where malicious scripts can exploit improper privilege boundaries to gain elevated permissions beyond their intended scope. Such flaws typically arise when the browser fails to properly enforce security contexts during navigation operations, allowing untrusted content to execute with higher privileges than permitted by the security model.
The technical implementation of this vulnerability involves manipulation of DOM navigation APIs that should normally be restricted to privileged contexts only. Attackers can craft malicious web content or exploit existing vulnerabilities in web applications to trigger navigation sequences that bypass normal privilege checks. This type of flaw often relates to CWE-284 which specifically addresses improper access control and inadequate privilege management within software systems. The vulnerability enables attackers to potentially execute arbitrary code with elevated privileges, access restricted resources, or perform actions that should be limited to trusted browser components.
Operational impact of this privilege escalation vulnerability is severe as it can lead to complete system compromise when exploited successfully. An attacker who successfully exploits this vulnerability could gain access to sensitive user data, perform unauthorized actions on behalf of the user, or even escalate to full system control depending on the execution environment and available privileges. The risk is particularly high in environments where users browse untrusted content or where browser security boundaries are already compromised through other attack vectors. This vulnerability affects not just individual user sessions but can potentially impact entire organizations if exploited at scale.
Mitigation strategies for this privilege escalation vulnerability include immediate deployment of Firefox version 153 or later which contains the necessary security patches and fixes. Organizations should also implement comprehensive browser hardening measures including strict content security policies, sandboxing mechanisms, and regular security updates to prevent exploitation of similar vulnerabilities. Additionally, monitoring systems should be configured to detect unusual navigation patterns or privilege escalation attempts within browser environments. The fix typically involves implementing stricter validation checks for DOM navigation operations and ensuring proper enforcement of security contexts during navigation handling processes, aligning with ATT&CK technique T1068 which covers privilege escalation through local exploitation methods.
This vulnerability demonstrates the critical importance of maintaining robust security boundaries within browser implementations and highlights the need for continuous security assessments of core browser components. The presence of such flaws in fundamental browser functionality underscores the necessity of comprehensive security testing including threat modeling, code reviews, and penetration testing to identify potential privilege escalation vectors before they can be exploited by malicious actors in real-world scenarios.