CVE-2026-117989 in Firefox
Summary
by MITRE • 10/27/2026
Use-after-free in the Graphics component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified vulnerability represents a critical memory management error classified as an out-of-bounds write, specifically manifesting through a use-after-free condition within the browser's graphics subsystem. In software engineering terms, this flaw occurs when the application continues to utilize a pointer after the memory it references has been deallocated and potentially reallocated for other purposes. This scenario typically arises in complex rendering pipelines where asynchronous operations or rapid state changes can lead to race conditions between object destruction and subsequent access attempts. The graphics component is particularly susceptible because it handles high-frequency updates, texture mapping, and compositing tasks that require precise synchronization of memory lifecycles across multiple threads. When a graphical element is removed from the display list but its underlying data structure remains referenced by an active process or callback, any write operation to this stale pointer results in writing data into arbitrary memory locations controlled by the allocator rather than the intended object buffer.
From a technical perspective, this vulnerability falls under CWE-416, which defines use-after-free errors as a subset of improper resource release vulnerabilities. The exploitation vector often involves crafting specific HTML or CSS content that triggers rapid creation and destruction of graphical objects, such as canvas elements, WebGL contexts, or SVG graphics layers. By carefully timing the deallocation of these resources while maintaining references through event listeners or animation frames, an attacker can manipulate the heap layout to overwrite adjacent memory structures. This may include overwriting function pointers in vtables, altering control flow data, or corrupting internal browser state variables that govern security checks and sandbox boundaries. The severity is amplified by the fact that modern browsers rely heavily on hardware-accelerated graphics APIs like OpenGL, Vulkan, or Direct3D, where incorrect memory access can lead to driver-level crashes or privilege escalation if the vulnerability allows for arbitrary code execution within a higher-privileged context.
The operational impact of this flaw extends beyond simple application instability. While immediate exploitation might result in denial-of-service conditions through browser crashes or hangs, sophisticated attackers leverage use-after-free vulnerabilities to achieve remote code execution with minimal user interaction. By achieving arbitrary read and write primitives via the corrupted memory state, an attacker can bypass modern mitigation techniques such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP). This capability allows for the establishment of a foothold on the victim's system, potentially leading to full compromise depending on the browser's sandboxing architecture. In enterprise environments running Firefox Extended Support Release versions, this vulnerability poses a significant risk due to the prolonged exposure window if updates are delayed, affecting thousands of endpoints simultaneously and increasing the attack surface for targeted campaigns or widespread malware distribution.
Mitigation strategies primarily focus on timely patch management as the definitive solution. Organizations must ensure that all instances of Mozilla Firefox, including both standard releases and Extended Support Release channels, are updated to version 159 and ESR 153.6 respectively, where this issue has been resolved through rigorous code review and memory safety improvements in the graphics stack. Beyond patching, defense-in-depth measures should be implemented to reduce exploitability. Enabling strict Content Security Policies helps limit the types of scripts that can interact with graphical elements, while disabling unnecessary plugins or features reduces the attack surface. Additionally, deploying endpoint detection and response solutions capable of monitoring for anomalous memory access patterns or unusual process behavior can provide early warning indicators of exploitation attempts. Regular security audits focusing on third-party libraries integrated into web applications also help prevent similar vulnerabilities from being introduced through external dependencies that interact with browser rendering engines.
This incident underscores the importance of continuous vulnerability management and rapid response protocols in maintaining cybersecurity posture. The integration of automated patching systems ensures that critical updates are applied without manual intervention, minimizing the window of exposure. Furthermore, fostering a culture of secure coding practices among developers working on core components like graphics processing can prevent recurrence by emphasizing proper memory lifecycle management and rigorous testing procedures such as fuzzing against edge cases in rendering logic.