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": "2026-09-15T13:16:48.243Z",
  "pubdate": "2026-09-15T13:16:48.243Z",
  "executiveSummary": "A privilege escalation vulnerability exists within the Graphics: CanvasWebGL component of Mozilla Firefox. The flaw arises from incorrect boundary condition handling, which may allow a malicious actor to bypass security constraints by manipulating memory structures associated with WebGL rendering operations.\nThe vulnerability affects Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, and Firefox ESR 153.3. Successful exploitation enables an attacker to elevate their privileges within the context of the application, potentially leading to unauthorized system access or sandbox escapes.\nThis vulnerability is critical as it leverages the complex nature of GPU-accelerated rendering to execute operations outside of intended memory boundaries. Attackers typically require the execution of crafted WebGL content within the browser to initiate the exploit. Users operating on affected versions are at risk of arbitrary code execution if the integrity of the CanvasWebGL component is compromised, making prompt application of security patches essential to maintain browser and system security posture.",
  "technicalDetails": "The root cause of this vulnerability lies in an improper boundary check within the Graphics: CanvasWebGL component, specifically during the handling of WebGL-related buffers or texture operations. When the component processes incoming WebGL commands, it fails to sufficiently validate the bounds of data being written to or read from memory, leading to an out-of-bounds access condition.\nThe attack flow begins when an attacker provides a specially crafted web page containing malicious WebGL shaders or geometry data. When the CanvasWebGL engine processes these inputs, the incorrect boundary condition allows the attacker to write data to, or read data from, memory locations that should remain inaccessible to the web content process. This violation of memory isolation allows an attacker to corrupt critical data structures, such as object pointers or function tables, stored within the same memory space as the graphics context.\nBy systematically triggering this boundary condition violation, an attacker can achieve a controlled write primitive. This primitive is then utilized to overwrite sensitive structures, potentially redirecting control flow to attacker-controlled memory. Given the nature of WebGL, this operation occurs within the Graphics component, which often operates with higher privileges or direct access to low-level hardware interfaces. Successful manipulation of these memory structures allows for privilege escalation, enabling the malicious code to break out of the browser's sandbox environment.\nThe vulnerability is persistent in versions prior to the noted fixes, as the Graphics component does not strictly enforce index and size limits during buffer updates or state transitions. Because this process occurs at the interface between the browser's high-level JavaScript API and the lower-level hardware acceleration layers, it is highly sensitive to input variance. No authentication is required for exploitation; an attacker simply needs to ensure the victim navigates to an environment where the vulnerable WebGL code is executed. The post-exploitation impact includes the potential for arbitrary code execution with the permissions of the browser process, significantly undermining the security of the host system."
}