CVE-2026-117986 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 security issue represents a critical memory management flaw within the graphics subsystem of Mozilla Firefox, specifically categorized as an use-after-free vulnerability. In software engineering terms, this type of defect occurs when a program continues to use a pointer after it has been freed from its allocated memory block. This scenario typically arises due to improper handling of object lifecycles where references are not properly invalidated or checked before access. The graphics component is particularly sensitive because it often handles complex data structures related to rendering, compositing, and hardware acceleration interfaces. When the underlying memory is deallocated but retained in a pointer variable within the application logic subsequent operations that rely on this stale reference can lead to unpredictable behavior, including crashes, data corruption, or potentially arbitrary code execution if an attacker can control the contents of the freed memory region.
From a technical perspective, use-after-free vulnerabilities are among the most dangerous classes of bugs because they provide attackers with significant leverage for exploitation. By carefully crafting malicious web content that triggers the specific sequence leading to premature deallocation and subsequent access, an adversary may be able to write controlled data into the reclaimed memory space. If this memory is then reallocated for a different purpose before being accessed again by the vulnerable code path, the attacker can influence how the application interprets that data. This mechanism allows for potential remote code execution with the privileges of the user running the browser process. The complexity lies in timing and heap grooming techniques required to ensure predictable behavior during exploitation, but modern exploit development frameworks have made such attacks increasingly feasible against complex applications like web browsers.
The operational impact of this vulnerability is severe given its location within the graphics stack which processes data from untrusted sources on the internet. A successful exploit could allow a remote attacker to bypass security restrictions and execute arbitrary code on the victim's system. This compromises the confidentiality, integrity, and availability of the user environment. Users visiting specially crafted web pages or interacting with malicious multimedia content could trigger the flaw without any additional interaction such as clicking prompts or installing software. The risk is amplified by the fact that graphics processing often involves direct access to hardware resources and low-level memory operations which are less sandboxed than standard JavaScript execution environments, thereby increasing the potential blast radius of a successful compromise.
Industry standards classify this vulnerability under CWE-416 Use After Free within the Common Weakness Enumeration framework. This classification highlights the fundamental error in resource management that leads to undefined behavior upon dereferencing freed memory. Furthermore from an offensive security perspective such as MITRE ATT&CK, exploitation techniques associated with use-after-free often fall under categories like Memory Corruption or potentially Code Injection depending on how the attacker leverages the vulnerability for further stages of compromise. Understanding these mappings helps in prioritizing remediation efforts and aligning patch deployment strategies with broader threat intelligence models that track similar exploit patterns across different software vendors.
Mitigation primarily relies on applying the vendor-provided updates which address the underlying memory management logic within the graphics component. For organizations managing large fleets, ensuring rapid distribution of Firefox version 159 and Firefox ESR 153.6 is essential to close this security gap. In addition to patching network segmentation strategies can help limit lateral movement if a compromise occurs while patches are being deployed. Users should also be advised against visiting untrusted websites or opening suspicious attachments until their software is fully updated. Continuous monitoring for indicators of exploitation and keeping all browser plugins and extensions up to date further reduces the attack surface associated with such high-severity memory corruption flaws.