CVE-2026-117917 in Firefox
Summary
by MITRE • 10/27/2026
Invalid pointer in the Graphics: WebRender component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security issue resides within the Mozilla Gecko rendering engine, specifically affecting the WebRender subsystem which is responsible for hardware-accelerated composition of web content. This component manages how graphical elements are drawn to the screen using GPU resources, and it processes complex layout instructions from modern web pages. The vulnerability manifests as an invalid pointer dereference, a critical memory safety flaw where the application attempts to access or manipulate a memory address that is either null, uninitialized, or otherwise not allocated for use by the program. In high-performance rendering engines like WebRender, such errors often occur during the processing of intricate CSS animations, complex SVG graphics, or WebGL contexts where pointer arithmetic and buffer management are intensive. When an invalid pointer is accessed, it indicates a breakdown in memory boundary checks or state validation logic within the compositor pipeline.
From a technical perspective, this type of vulnerability falls under CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer or more specifically CWE-476 NULL Pointer Dereference depending on whether the invalid pointer is null or points to an arbitrary location in memory. The operational impact of such a flaw can range from benign visual glitches and rendering artifacts to severe security consequences including denial of service through application crashes, or potentially remote code execution if the attacker can control the data written to or read from that invalid memory region. In modern browsers, sandboxing mechanisms are designed to mitigate these risks by restricting what compromised renderer processes can do with system resources. However, a successful exploitation could allow an adversary to bypass certain isolation boundaries, leading to information disclosure of sensitive user data stored in adjacent memory spaces or facilitating further attacks against the host operating system if additional vulnerabilities exist within the browser's privilege-separated architecture.
This vulnerability was addressed and patched in Firefox version 159 as well as extended support release versions 115.44 and 153.6, ensuring that users running these updated builds are protected against exploitation attempts targeting this specific memory safety defect. The fix likely involved strengthening input validation for graphical primitives added to the rendering queue and implementing stricter checks on pointer validity before they are passed to low-level graphics APIs such as Vulkan or OpenGL ES. To mitigate similar risks in broader software development, it is recommended that developers adhere strictly to safe coding practices regarding dynamic memory allocation and utilize static analysis tools capable of detecting uninitialized variable usage and out-of-bounds accesses during the code review phase. Additionally, enabling compiler-based protections like AddressSanitizer during testing phases can help identify such issues before deployment.
For end-users and system administrators, maintaining up-to-date browser installations is the primary defense against exploitation of these types of vulnerabilities. Organizations should enforce automated patch management policies to ensure that all endpoints receive security updates promptly upon release. Furthermore, deploying endpoint detection and response solutions with behavioral analysis capabilities can help identify anomalous processes spawned by a compromised renderer process, providing an additional layer of defense in depth. The ATT&CK framework categorizes such exploitation techniques under T1203 Exploitation for Client Execution or potentially T1059 Command and Scripting Interpreter if the vulnerability leads to arbitrary code execution within the browser context, highlighting the importance of monitoring for suspicious script activity originating from web content processes.