Description

Privilege escalation in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-09-15T13:16:57.053Z",
  "pubdate": "2026-09-15T13:16:57.053Z",
  "executiveSummary": "This vulnerability involves a privilege escalation flaw identified within the Graphics: CanvasWebGL component of the Mozilla Firefox browser. The flaw permits an attacker to circumvent existing browser security boundaries to execute code or perform unauthorized operations with elevated privileges. The vulnerability resides in how the CanvasWebGL subsystem manages memory or resource states during complex rendering tasks. Successful exploitation allows a remote attacker to escalate privileges, potentially leading to unauthorized system access or arbitrary code execution within the security context of the application. This vulnerability is particularly critical due to the ubiquity of WebGL in web-based graphics processing. The issue is resolved in Firefox 156 and Firefox ESR 153.3, and users are advised to update immediately. No specific user interaction is mentioned as a prerequisite beyond navigating to a malicious web page, making this a high-risk security flaw for unpatched systems.",
  "technicalDetails": "The vulnerability resides within the Graphics: CanvasWebGL component, specifically concerning the interface between the browser's high-level WebGL API and the underlying graphics subsystem. The root cause is a flaw in memory management or object lifetime tracking during the initialization or destruction of WebGL contexts. When a web application invokes specific WebGL function calls, the browser's Graphics: CanvasWebGL component fails to properly validate the state of the rendering context, leading to a state of memory corruption or an invalid object reference.\nThe exploitation flow typically begins when a malicious actor crafts a web page containing a series of specifically ordered WebGL commands. These commands are designed to trigger a race condition or a use-after-free scenario within the CanvasWebGL internal resource management buffers. By carefully orchestrating the allocation and deallocation of WebGL-related buffers, an attacker can coerce the component into accessing a memory address that has already been deallocated or repurposed. This manipulation allows for the overwriting of internal browser structures, such as function pointers or vtables, which are then hijacked to redirect the flow of execution.\nThe attack is performed without the requirement of local authentication, as the browser automatically executes scripts from untrusted domains. Because the vulnerability lies within the browser's core rendering pipeline, the exploit executes with the privileges of the Firefox process. If the browser process has sufficient system-level permissions or is not sufficiently sandboxed, the attacker can leverage the memory corruption to break out of the content sandbox, resulting in a full privilege escalation. The impact includes the execution of arbitrary code within the user's system environment, potentially bypassing memory protection mechanisms such as ASLR or DEP through careful payload engineering during the heap grooming phase.\nThe vulnerability affects all versions of Firefox prior to 156 and Firefox ESR prior to 153.3. The lack of proper input sanitization and context state validation allows for this class of memory-based vulnerability. Once the exploitation is successful, the attacker gains the ability to execute instructions in the context of the browser, which can be used to exfiltrate sensitive data, install persistent malware, or manipulate local system files depending on the environmental constraints and the effectiveness of the platform's security sandbox."
}