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": "2026-09-15T13:16:49.310Z",
  "pubdate": "2026-09-15T13:16:49.310Z",
  "executiveSummary": "A privilege escalation vulnerability exists within the Graphics: CanvasWebGL component of Mozilla Firefox, stemming from incorrect handling of boundary conditions. This flaw allows a remote attacker to potentially bypass browser security sandboxing mechanisms by exploiting memory management errors during WebGL operations. Successfully leveraging this vulnerability enables an attacker to execute arbitrary code or gain elevated system privileges within the context of the affected application. The vulnerability affects Firefox 156, Firefox ESR 115.41, Firefox ESR 140.16, and Firefox ESR 153.3. The security implications are severe, as exploitation does not necessarily require complex user interaction beyond navigating to a malicious web page designed to trigger the boundary condition failure. Users are urged to upgrade to the specified patched versions immediately to remediate the risk of unauthorized system access or compromise.",
  "technicalDetails": "The vulnerability resides in the Graphics: CanvasWebGL component, specifically involving the validation logic used to enforce boundary constraints during memory buffer operations. In the context of WebGL, the browser interfaces with the underlying graphics driver to render content; incorrect boundary condition handling suggests that the implementation fails to adequately validate the size and bounds of input data before processing or copying operations within the GPU-related memory buffers.\nThe root cause is identified as an improper verification of parameters passed to the WebGL API, leading to out-of-bounds memory access. When a malicious web page submits crafted WebGL commands, the component fails to correctly enforce internal constraints, potentially allowing a buffer overflow or an out-of-bounds read/write condition. This violation of memory safety occurs when the browser logic assumes that provided indices or lengths fall within a safe allocated range, but they actually extend into memory regions controlled by the attacker or sensitive system data.\nThe exploitation flow typically begins with an attacker embedding malicious JavaScript or WebGL shader code within a web page. When rendered, this code triggers a specific sequence of WebGL calls designed to manipulate the internal state of the CanvasWebGL component. By carefully orchestrating these calls, an attacker can induce a heap-based buffer overflow or memory corruption. Once the memory is corrupted, the attacker can leverage the primitive to overwrite function pointers or object vtables, redirecting the control flow of the browser process. Because the browser process often executes with higher effective privileges than the web content itself, this control flow hijack facilitates privilege escalation, allowing the attacker to escape the browser sandbox and execute arbitrary native code on the host operating system.\nThe vulnerability is present in Firefox versions prior to 156 and specific ESR branches including 115.41, 140.16, and 153.3. Exploitation is remote and does not require pre-existing authentication. The attack surface is exposed via the browser's graphics rendering engine, and the post-exploitation impact includes full code execution, persistence, and potential escalation to system-level access depending on the OS-level security policies and the sandbox's integrity."
}