CVE-2026-117979 in Firefox
Summary
by MITRE • 10/27/2026
Incorrect boundary conditions 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 WebRender subsystem of Mozilla Firefox, specifically concerning incorrect boundary conditions during graphics processing operations. WebRender is a critical component responsible for rendering web content efficiently by leveraging hardware acceleration through OpenGL or Vulkan APIs. When handling complex layout calculations and rasterization tasks, the engine must strictly adhere to memory boundaries defined by allocated buffers and texture dimensions. The vulnerability arises when these boundary checks are either omitted or implemented incorrectly, allowing operations to proceed beyond the intended limits of a data structure. This type of flaw is characteristic of out-of-bounds access vulnerabilities where the software fails to validate that an index or offset remains within the permissible range of a buffer before performing read or write operations.
From a technical perspective, this boundary condition error likely manifests as either an out-of-bounds read or an out-of-bounds write depending on how the flawed logic is triggered during rendering pipelines. In cases involving reads, an attacker could potentially leak sensitive information from adjacent memory regions that were not intended to be accessed by the web page context. If the flaw permits writes, it may lead to heap corruption, which can result in arbitrary code execution if the corrupted data structures are later used for control flow decisions or function pointer dereferences. Such vulnerabilities often stem from complex interactions between JavaScript engine allocations and native C++ graphics routines where type conversions or integer overflows might bypass expected safety checks. The presence of this flaw indicates a gap in input validation logic within the rendering path, particularly when processing malformed CSS properties, SVG elements, or canvas operations that trigger specific code paths with insufficient boundary verification.
The operational impact of exploiting this vulnerability is significant as it allows for remote code execution through malicious web content. An attacker would need to host a specially crafted webpage containing exploit code designed to trigger the incorrect boundary condition within WebRender. Upon visiting this page, the browser processes the malformed graphics commands, leading to memory corruption or information disclosure without user interaction beyond navigation. This aligns with common attack vectors described in industry standards such as CWE-125 for out-of-bounds read and CWE-787 for out-of-bounds write. Furthermore, from a threat modeling perspective utilizing the MITRE ATT&CK framework, this vulnerability facilitates initial access via drive-by download techniques (T1189) and potentially privilege escalation if combined with other local exploits to gain system-level control. The ability to execute arbitrary code in the context of the browser process poses severe risks including data theft, keylogging, or using the compromised machine as a pivot point for further network attacks.
Mitigation strategies primarily involve applying the software updates released by Mozilla that address these specific boundary checks within WebRender. Users should ensure they are running Firefox version 159 or later, or the Extended Support Release versions 115.44 and 153.6 which contain the necessary patches to validate memory access boundaries correctly. For organizations managing large deployments of browsers, automated patch management systems should be configured to prioritize these updates due to their severity in enabling remote code execution. Additionally, defense-in-depth measures such as enabling strict Content Security Policies can help mitigate some downstream effects by restricting script execution contexts, although they do not directly prevent low-level memory corruption vulnerabilities like this one. Regular security audits of rendering engines and adherence to secure coding practices that emphasize rigorous input validation are essential for preventing similar boundary condition flaws in future software versions.