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": "2026-09-15T13:16:48.463Z",
  "pubdate": "2026-09-15T13:16:48.463Z",
  "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 within the rendering engine.\nThe vulnerability poses a significant risk to system integrity, as successful exploitation enables an attacker to elevate privileges beyond the sandbox environment. This typically involves crafting malicious WebGL content designed to trigger out-of-bounds memory access or logic errors during GPU-accelerated rendering operations.\nImpacted products include Firefox, Firefox ESR 115, Firefox ESR 140, and Firefox ESR 153. Given the nature of browser-based exploitation, this vulnerability can be leveraged via drive-by downloads or malicious web content, requiring minimal user interaction beyond visiting a compromised page.\nThe primary risk implication is the potential for arbitrary code execution in the context of the privileged browser process, which could lead to full system compromise depending on the effectiveness of the underlying OS-level sandbox. Remediation requires updating the browser to the specified secure versions.",
  "technicalDetails": "The vulnerability resides within the Graphics: CanvasWebGL component, specifically involving the processing of buffer inputs or state transitions during WebGL context initialization and resource management. The root cause is identified as an improper validation of boundary conditions when the GPU process handles incoming command streams or memory allocation requests.\nIn the context of the WebGL pipeline, the browser must ensure that memory operations, such as vertex buffer object (VBO) access or texture coordinate calculations, stay within the defined bounds of allocated memory buffers. An incorrect boundary condition allows an attacker to supply manipulated inputs that force the renderer to read or write data outside of the intended memory region (out-of-bounds access).\nThe exploitation flow typically begins with the victim navigating to a malicious website containing crafted JavaScript that interacts with the CanvasWebGL API. The attacker leverages specific WebGL commands—likely involving complex shader programs or malformed draw calls—to trigger the boundary condition error. By carefully spraying memory and controlling the contents of adjacent heap structures, the attacker can influence the state of the GPU process.\nBecause the CanvasWebGL component operates within the browser's graphics subsystem, successful exploitation can result in a transition from the untrusted content sandbox to a higher-privilege browser process. This is achieved by overwriting function pointers or sensitive object metadata in memory, effectively hijacking the control flow of the browser's execution thread.\nThis vulnerability affects Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, and Firefox ESR 153.3. There are no authentication requirements; however, the exploit requires the ability to execute JavaScript within the target's browser. The network exposure is high, as the vulnerability is triggerable via any web page that can initialize a WebGL context. The post-exploitation impact is severe, potentially granting the attacker persistence or the ability to execute arbitrary native code on the host operating system, bypassing standard browser-level security restrictions."
}