CVE-2026-92012 in Firefox
Summary
by MITRE • 09/15/2026
Privilege escalation due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The identified vulnerability resides within the Graphics: CanvasWebGL component of Mozilla Firefox, representing a critical class of security flaws known as privilege escalation via incorrect boundary conditions. This specific defect allows an attacker to bypass intended access controls by manipulating input parameters that exceed expected limits or fail to validate data ranges properly during WebGL rendering operations. In modern web browsers, the canvas element and its associated WebGL context provide powerful graphics capabilities but also expose complex interfaces between JavaScript execution environments and lower-level system resources. When boundary checks are insufficient or incorrectly implemented within these components, it creates an opportunity for malicious actors to craft specially designed HTML pages containing exploit code that triggers undefined behavior in the browser's rendering engine.
The technical nature of this flaw involves a failure to properly enforce memory safety constraints during WebGL context initialization or shader compilation processes. Specifically, the vulnerability likely stems from improper validation of array indices, buffer sizes, or uniform variable limits passed by JavaScript scripts to native C++ code handling graphics operations. This lack of rigorous boundary checking can lead to out-of-bounds reads or writes in adjacent memory structures. Such memory corruption issues are particularly dangerous because they allow for arbitrary read and write primitives, which serve as the foundational building blocks for more sophisticated attacks including heap spraying and control flow hijacking. The presence of this flaw indicates a gap in the sanitization logic that should normally isolate untrusted web content from privileged browser processes.
From an operational impact perspective, successful exploitation of this vulnerability enables remote code execution with elevated privileges within the context of the user's current session. An attacker could potentially access sensitive data stored by other websites due to same-origin policy bypasses facilitated through memory corruption, or execute arbitrary commands on the underlying operating system if further chaining opportunities exist. This compromises the fundamental security model of web browsers which relies heavily on process isolation and sandboxing mechanisms. Users visiting a maliciously crafted website containing exploit code could find their systems compromised without any additional interaction beyond loading the page, highlighting the severity of client-side vulnerabilities in widely used software like Firefox.
Industry standards classify this type of vulnerability under CWE-120 Buffer Copy without Checking Size of Input or CWE-787 Out-of-bounds Write depending on the exact manifestation within the WebGL pipeline. These classifications emphasize the importance of rigorous input validation and bounds checking in systems programming languages often used for browser engines such as C++. Furthermore, from a threat intelligence standpoint aligned with MITRE ATT&CK frameworks, this vulnerability facilitates techniques related to Initial Access through Drive-by Code Execution and potentially Privilege Escalation if combined with other local exploits. The exploitation vector is typically classified as Network-based where the attacker delivers malicious content via web pages rather than requiring direct system access or user interaction beyond visiting a site.
Mitigation strategies primarily involve applying the software updates released by Mozilla that address these boundary condition checks within the CanvasWebGL component. Users should ensure their browsers are updated to Firefox version 156, Firefox Extended Support Release (ESR) version 115.41, ESR version 140.16, or ESR version 153.3 as specified in the advisory. These patches likely include enhanced validation routines for WebGL parameters and stricter enforcement of memory boundaries during graphics processing tasks. In environments where immediate patching is not feasible, network-level controls such as web application firewalls can be configured to detect and block requests containing suspicious patterns associated with WebGL exploitation attempts although this approach offers limited protection against sophisticated zero-day attacks. Additionally enabling sandboxing features provided by the operating system adds an extra layer of defense limiting the potential impact if a browser process is compromised through similar vulnerabilities in other components.