CVE-2026-92058 in Firefox
Summary
by MITRE • 09/15/2026
Use-after-free in the Graphics component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security issue represents a critical memory management flaw within the Mozilla Gecko rendering engine, specifically categorized as an out-of-bounds write resulting from use-after-free conditions. In software architecture, particularly in complex graphics processing units like those found in Firefox's composition and layout engines, objects are frequently allocated on the heap to handle visual elements such as layers, frames, or compositor data structures. A use-after-free vulnerability occurs when a program continues to use a pointer after that memory has been freed back to the system allocator. In this specific instance within the Graphics component, the application fails to properly invalidate references to an object once its lifecycle ends, allowing subsequent operations to access deallocated memory regions. This type of flaw is formally classified under CWE-416 in the Common Weakness Enumeration standard, which highlights the danger of referencing freed memory that may have been reallocated for different purposes or contain sensitive data from previous allocations.
The operational impact of this vulnerability is severe because it allows an attacker to achieve arbitrary code execution with the privileges of the user running the browser. By carefully crafting a malicious webpage containing specific JavaScript and HTML elements, an adversary can trigger the race condition that leads to the use-after-free state. Once the memory is accessed after being freed, the attacker can manipulate the contents of that memory region through heap spraying techniques or by controlling the allocation patterns of subsequent objects. This manipulation enables the overwriting of function pointers or object vtables within the graphics subsystem. When these corrupted structures are invoked during normal rendering operations, control flow hijacking occurs, allowing the execution of arbitrary shellcode on the victim's machine. The vulnerability was addressed in Firefox version 156 and Firefox Extended Support Release (ESR) version 153.3 through rigorous code reviews that introduced proper nullification of pointers after deallocation and enhanced bounds checking within the graphics pipeline to prevent access to invalid memory addresses.
From a threat intelligence perspective, this exploitation technique aligns with ATT&CK tactic T1203, which covers Exploitation for Client Execution, specifically leveraging client-side software vulnerabilities in web browsers. Attackers typically distribute such exploits via phishing campaigns or compromised websites that host the malicious payload. The graphics component is particularly attractive to attackers because it operates at a low level within the browser process and often handles untrusted input from rendered content directly. Mitigation strategies for organizations rely heavily on ensuring all endpoints are updated with the latest patches of Firefox 156 or ESR 153.3, as these versions contain the specific fixes that close the window of opportunity for exploitation. Additionally, deploying browser isolation solutions or strict Content Security Policies can reduce the attack surface by preventing untrusted scripts from interacting deeply with the rendering engine's internal structures. Regular security audits focusing on memory safety in C and C++ codebases are also recommended to prevent similar defects in future releases, as use-after-free bugs remain one of the most prevalent causes of critical browser vulnerabilities.