CVE-2026-92079 in Firefox
Summary
by MITRE • 09/15/2026
Mitigation bypass in the Widget: Win32 component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The reported issue pertains to a mitigation bypass within the Win32 widget component of Mozilla Firefox, specifically affecting versions prior to Firefox 156 and Firefox Extended Support Release (ESR) 153.3. This vulnerability highlights a failure in the operating system's security mechanisms or their implementation within the browser's native interface layer, allowing an attacker to circumvent intended protective controls. Such bypasses are particularly critical because they undermine foundational defense-in-depth strategies that rely on strict isolation and privilege separation between different parts of an application and the underlying host system.
From a technical perspective, mitigation bypass vulnerabilities often stem from improper validation of security policies or incorrect handling of inter-process communication boundaries. In the context of browser widgets, this may involve manipulating window handles, message queues, or UI elements to execute code in a higher privilege context than intended, or to access memory regions that should be restricted. The Win32 component serves as the bridge between Firefox's internal rendering engine and the Windows operating system's graphical user interface subsystem. If security mitigations such as Data Execution Prevention (DEP), Address Space Layout Randomization (ASLR), or structured exception handling protections are not correctly enforced during widget operations, an attacker could potentially leverage this gap to achieve arbitrary code execution or escalate privileges on the compromised host machine.
The operational impact of this vulnerability is significant for end-users and enterprise environments alike. Successful exploitation could allow a remote attacker who tricks a user into visiting a malicious webpage containing crafted content to bypass security boundaries established by the browser sandbox. This can lead to full system compromise, data exfiltration, or installation of persistent malware without triggering standard antivirus or endpoint detection responses that rely on these mitigations for threat identification. The severity is further amplified in enterprise settings where Firefox may be deployed with specific group policies and security configurations; a bypass effectively nullifies those controls, leaving the network perimeter vulnerable to lateral movement attacks initiated from the compromised workstation.
This type of flaw aligns closely with CWE-250, which describes execution with unnecessary privileges, or potentially CWE-787 if it involves out-of-bounds access leading to code execution due to weakened memory safety checks. In terms of offensive security frameworks, this vulnerability facilitates techniques categorized under MITRE ATT&CK T1204, specifically User Execution and Malicious Software, as well as potential privilege escalation vectors like T1068 Exploitation for Privilege Escalation if the bypass allows access to higher integrity levels within Windows. The ability to circumvent mitigations is a critical step in advanced persistent threat campaigns that aim to establish long-term footholds on corporate networks by exploiting trusted applications with elevated trust relationships.
Mitigation of this vulnerability requires immediate patching as outlined by Mozilla, upgrading all affected instances to Firefox 156 or Firefox ESR 153.3 and later versions where the underlying security controls have been corrected. Organizations should enforce automated update policies to ensure rapid deployment of these fixes across their desktop estate. Additionally, implementing application whitelisting solutions can restrict the execution of unapproved binaries even if a mitigation bypass is exploited, providing an additional layer of defense. Network segmentation and strict egress filtering further reduce the blast radius by limiting communication channels that malware might use after gaining initial access through such browser-based vulnerabilities. Regular security awareness training for users also remains essential to prevent social engineering tactics that often precede exploitation of these types of technical flaws.