CVE-2026-92009 in Firefox
Summary
by MITRE • 09/15/2026
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.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security flaw resides within the CanvasWebGL component of Mozilla Firefox, specifically involving incorrect boundary conditions that facilitate privilege escalation. This vulnerability stems from a failure in the software to properly validate input data or memory indices when processing WebGL operations, allowing an attacker to write to arbitrary locations in memory outside the intended boundaries. Such out-of-bounds writes are particularly dangerous because they can corrupt adjacent memory structures, potentially overwriting critical control flow data such as return addresses or function pointers. In the context of a web browser, this mechanism enables code execution within the process sandbox with higher privileges than those granted to standard web content, effectively breaking the isolation model that protects users from malicious websites.
From a technical perspective, this issue aligns closely with CWE-190, which describes integer overflow or wraparound errors, and CWE-787, which covers out-of-bounds write vulnerabilities. The root cause likely involves insufficient checks on array indices or buffer sizes during the rendering pipeline of WebGL contexts. When a malicious webpage constructs specific graphics commands that trigger these boundary failures, it can manipulate the internal state of the browser engine. This manipulation allows for arbitrary read and write operations in memory space allocated to privileged components like the GPU process or main thread handlers. The exploitation chain typically involves crafting a specially designed HTML page with embedded JavaScript and WebGL shaders that force the renderer into an invalid state, leading to heap corruption or stack overflow scenarios that can be leveraged to execute shellcode.
The operational impact of this vulnerability is severe due to its potential for remote code execution without user interaction beyond visiting a compromised website. Attackers could use this flaw to bypass browser sandboxing mechanisms, gaining access to sensitive data stored locally on the victim's machine, such as cookies, saved passwords, and session tokens. Furthermore, successful exploitation could allow the installation of persistent malware or serve as an initial vector for more complex attacks targeting system-level services. The ability to escalate privileges within the browser process significantly increases the blast radius of a single compromised webpage, transforming what might otherwise be contained script execution into a full system compromise if additional vulnerabilities are chained together.
Mitigation strategies primarily rely on applying the vendor-provided patches released in Firefox version 156 and the respective Extended Support Release versions including ESR 115.41, ESR 140.16, and ESR 153.3. These updates contain code changes that enforce stricter boundary checks within the CanvasWebGL implementation, ensuring that memory accesses remain within allocated limits. Organizations should prioritize updating all instances of Firefox to these patched versions immediately to close this attack surface. In environments where immediate patching is not feasible, network-level controls such as web filtering proxies can be configured to block access to known malicious domains or restrict WebGL functionality entirely for untrusted users. Additionally, enabling strict Content Security Policies and disabling unnecessary browser features like JavaScript in high-risk zones can reduce the likelihood of successful exploitation by limiting the attack vectors available to adversaries.
This vulnerability is categorized under ATT&CK technique T1059, which covers command and script interpreter abuse, as well as T1203 for exploit execution. The specific nature of the flaw relates to memory corruption techniques often associated with CWE-787 out-of-bounds writes. Security teams should monitor for indicators of compromise that suggest attempts to leverage WebGL-based exploits, such as unusual network traffic patterns or unexpected process behavior originating from browser instances. Regular vulnerability scanning and penetration testing focused on web application security can help identify similar boundary condition issues in other components before they are exploited in the wild. Maintaining up-to-date threat intelligence feeds is also crucial for detecting emerging exploit kits that may target this specific Firefox weakness.