Description

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.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-09-15T13:16:48.740Z",
  "pubdate": "2026-09-15T13:16:48.740Z",
  "executiveSummary": "A privilege escalation vulnerability exists within the Graphics: CanvasWebGL component of the Mozilla Firefox browser. The flaw arises from incorrect boundary condition handling during memory operations. If successfully exploited, this vulnerability allows a malicious actor to elevate their privileges within the context of the application, potentially bypassing sandbox constraints or gaining unauthorized access to system resources. The issue affects Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, and Firefox ESR 153.3. The risk implications are significant, as successful exploitation could lead to arbitrary code execution or a compromise of the browser security model. Attackers must typically lure a user to a malicious web page to trigger the vulnerability. Exploitation does not require prior authentication, but it does rely on the victim interacting with specially crafted web content that interacts with the WebGL API.\nThis vulnerability highlights a critical breakdown in input validation within the graphics processing pipeline, specifically where the Canvas element interfaces with WebGL. Given that graphics drivers and browser APIs often operate with high-level access, improper bounds checking can lead to memory corruption, allowing an attacker to manipulate the browser process memory space.",
  "technicalDetails": "The root cause of this vulnerability lies in an improper boundary condition check within the Graphics: CanvasWebGL component. WebGL (Web Graphics Library) is a JavaScript API for rendering high-performance 2D and 3D graphics within any compatible web browser without the use of plug-ins. By interacting with the underlying graphics hardware via the GPU process, the CanvasWebGL component processes complex data structures and vertex/fragment shaders.\nThe vulnerability manifests when the component fails to correctly validate the bounds of data buffers or indices provided to the WebGL API. Because WebGL allows for direct interaction with graphics memory, an incorrect boundary condition can lead to an out-of-bounds (OOB) memory access. This may result in an out-of-bounds read or write operation within the memory space allocated to the browser's graphics rendering pipeline.\nThe exploitation flow typically begins with an attacker injecting malicious JavaScript into a compromised or attacker-controlled website. When a victim accesses this page using an affected version of Firefox, the script initiates a series of WebGL calls designed to trigger the boundary condition error. By carefully crafting the input values—such as array sizes, texture dimensions, or vertex buffer offsets—an attacker can force the CanvasWebGL component to perform operations outside of its designated memory boundaries.\nUpon triggering this memory corruption, an attacker could potentially overwrite critical data structures, such as function pointers or object headers. This level of memory manipulation facilitates arbitrary code execution within the security context of the affected process. In many browser architectures, compromising the rendering or GPU process is a primary step toward achieving a full sandbox escape, allowing the attacker to interact with the underlying operating system with higher privileges than those typically afforded to web content.\nAffected versions include Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, and Firefox ESR 153.3. The vulnerability does not require authentication, but it does necessitate that the browser's graphics acceleration be active and that the victim successfully loads the exploit-laden content. Post-exploitation, an attacker can maintain persistence, exfiltrate user data, or execute arbitrary payloads on the host system, depending on the success of the sandbox bypass methodology employed."
}