CVE-2026-74941 in Firefox
Summary
by MITRE • 08/18/2026
Privilege escalation in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1.
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Analysis
by VulDB Data Team • 08/19/2026
The identified security issue resides within the CanvasWebGL subsystem of Mozilla Firefox, specifically involving a privilege escalation flaw that allows an attacker to bypass intended access controls. This component is responsible for rendering interactive graphics using WebGL technology directly in the browser environment. The vulnerability stems from improper handling of context boundaries or resource permissions during the execution of JavaScript commands that interact with the GPU-accelerated canvas elements. When triggered, this defect enables a malicious web page or script operating under standard user privileges to execute code or access resources that should be restricted to higher-privileged contexts, such as those associated with browser internals or other tabs. This type of flaw is categorized under CWE-269 Improper Privilege Management and aligns with the ATT&CK technique T1055 Process Injection when considering how malicious actors might leverage elevated permissions to inject code into legitimate processes for persistence or further exploitation.
The operational impact of this vulnerability is significant because it undermines the browser's sandboxing model, which is critical for isolating untrusted web content from the host operating system and user data. An attacker could exploit this flaw by crafting a malicious webpage that utilizes WebGL commands to trigger the privilege escalation mechanism. Once successful, the attacker gains the ability to perform actions typically reserved for trusted code, such as accessing sensitive DOM elements across different origins, reading cookies or local storage from other sites, or potentially executing arbitrary system calls if combined with other vulnerabilities in the browser's rendering pipeline. This effectively breaks the cross-origin isolation policy that protects users from malicious websites attempting to steal data or hijack sessions. The risk is particularly acute for users who frequently visit untrusted or compromised websites, as well as enterprise environments where browsers are used to access sensitive internal applications over trusted networks but may still encounter drive-by download attacks via third-party advertising scripts or embedded content.
Mitigation strategies primarily rely on the immediate application of vendor-provided patches. Users must update their Firefox installation to version 154 or later, ensure that Firefox Extended Support Release (ESR) versions are updated to at least 140.14 for the ESR 128 branch and 153.1 for newer ESR branches. These updates contain code changes that enforce stricter validation checks on WebGL context creation and resource access permissions, thereby preventing unauthorized privilege elevation. In addition to software updates, organizations should implement strict Content Security Policy (CSP) headers to restrict the execution of inline scripts and limit sources from which WebGL content can be loaded. Deploying browser isolation solutions or using hardened security profiles that disable unnecessary JavaScript features in untrusted zones can further reduce the attack surface. Regular monitoring for anomalous behavior related to GPU resource usage may also help detect exploitation attempts before significant damage occurs, although proactive patch management remains the most effective defense against this class of vulnerability.