CVE-2026-92054 in Firefox
Summary
by MITRE • 09/15/2026
Privilege escalation in the Memory 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 privilege escalation flaw located within the memory management subsystem of Mozilla Firefox, specifically affecting versions prior to 156 and Firefox Extended Support Release (ESR) version 153.3. In modern web browsers, the memory component is responsible for allocating, managing, and deallocating heap space used by JavaScript engines and rendering processes. When this subsystem contains a vulnerability that allows privilege escalation, it implies that an attacker can manipulate internal state or data structures in such a way that they bypass intended security boundaries. This typically involves exploiting race conditions, use-after-free errors, or integer overflows within the memory allocator to gain unauthorized access to higher-privileged contexts, potentially allowing code execution with elevated system rights beyond what is permitted for standard web content processes.
From a technical perspective, privilege escalation vulnerabilities in browser components are particularly dangerous because they undermine the fundamental sandboxing model that protects users from malicious websites. The Memory component often operates at a lower level than the main UI thread or network stack, giving it broader access to system resources and sensitive data structures. An attacker could craft a specialized web page containing malicious JavaScript or embedded content designed to trigger this flaw during memory allocation or deallocation phases. By carefully controlling the timing and size of allocations, an adversary might corrupt internal pointers or metadata, leading to arbitrary read-write capabilities within the browser process context. This capability can be chained with other vulnerabilities to achieve full remote code execution on the victim's machine, effectively breaking out of the sandboxed environment that isolates web content from the host operating system.
The operational impact of this vulnerability is severe, as it enables a wide range of malicious activities including data theft, installation of persistent malware, and complete compromise of the user’s device. If an attacker successfully exploits this flaw, they can access sensitive information such as saved passwords, cookies containing session tokens, browsing history, and potentially credentials for other applications if those are stored in accessible memory regions. Furthermore, elevated privileges allow the attacker to interact with local system APIs, modify registry keys on Windows systems, or alter configuration files that control security settings. This transforms a simple cross-site scripting scenario into a high-severity remote code execution event, significantly increasing the risk profile for organizations and individual users who rely on Firefox as their primary web browser.
To mitigate this threat, it is imperative to update all instances of Mozilla Firefox to version 156 or later, and Firefox ESR installations must be upgraded to at least version 153.3 immediately upon availability. These updates contain the necessary patches that correct the underlying logic errors in the memory management routines, ensuring proper bounds checking and safe handling of dynamic allocations. Organizations should enforce automated patching policies through enterprise deployment tools to ensure timely remediation across all endpoints. Additionally, users can reduce their exposure by disabling JavaScript for untrusted sites or using browser extensions that restrict script execution on suspicious domains until patches are applied. Monitoring security advisories from Mozilla is also recommended to stay informed about any related follow-up fixes or workarounds provided during the transition period between vulnerable and patched versions.
This vulnerability aligns with Common Weakness Enumeration (CWE) categories such as CWE-269 Improper Privilege Management, which covers cases where an actor gains capabilities without proper authorization, and potentially CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer if heap corruption is involved. In terms of attack tactics, this flaw supports techniques described in the MITRE ATT&CK framework under Initial Access via Exploit Public-Facing Application or Defense Evasion through Process Injection, depending on how the elevated privileges are leveraged post-exploitation. Understanding these classifications helps security teams prioritize remediation efforts and configure detection rules to identify potential exploitation attempts targeting this specific component weakness.