CVE-2026-92067 in Firefox
Summary
by MITRE • 09/15/2026
Use-after-free in the Widget: Gtk 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 vulnerability represents a critical memory management error classified as an out-of-bounds write, specifically manifesting through a use-after-free condition within the Gecko rendering engine's Widget: Gtk component. This flaw occurs when the application attempts to access or manipulate a memory region that has already been deallocated by the system. In the context of Firefox and its underlying architecture, this typically involves UI elements managed via GTK+ on Linux-based operating systems where object lifecycles are not strictly synchronized with their references in the event loop or widget hierarchy. When an object is freed but retains active pointers within internal data structures, subsequent operations targeting those pointers result in undefined behavior rather than a controlled exception. This specific instance highlights a failure in reference counting mechanisms or pointer invalidation protocols during the lifecycle of GTK widgets, allowing for arbitrary memory writes if the attacker can control the content that overwrites the freed memory region.
From an operational perspective, this vulnerability poses severe risks to system stability and security integrity. The immediate consequence is often application instability, characterized by crashes or segmentation faults when the corrupted pointer triggers a fault in protected memory areas. However, the more critical risk lies in potential remote code execution. If an attacker can craft malicious web content that triggers this specific widget state transition, they may achieve arbitrary write primitives. These primitives allow for overwriting function pointers, virtual table entries, or other control data structures within the browser process. Such exploitation techniques are frequently associated with advanced persistent threats and zero-day campaigns targeting high-value assets. The ability to execute code in the context of the browser process significantly expands the attack surface, potentially leading to full system compromise if sandboxing mechanisms fail to contain the breach or if additional vulnerabilities exist that facilitate escape from the browser's security boundaries.
The technical classification aligns with Common Weakness Enumeration CWE-416, which defines use-after-free errors as a distinct category of memory corruption bugs. These flaws are particularly dangerous because they rely on race conditions or logical errors in object management rather than simple buffer overflows, making them harder to detect through static analysis alone. Furthermore, the exploitation strategy typically involves heap spraying techniques combined with precise timing attacks to ensure that the freed memory is reallocated for attacker-controlled data before it is accessed again. This aligns with MITRE ATT&CK technique T1203, which covers Exploitation for Client Execution, as well as potential lateral movement vectors if the browser process serves as a pivot point within an enterprise network environment. The vulnerability underscores the complexity of maintaining memory safety in large-scale C++ codebases where manual memory management is still prevalent despite modern best practices favoring smart pointers and RAII patterns.
Mitigation strategies primarily rely on timely patch deployment, as evidenced by the resolution in Firefox version 156 and Firefox Extended Support Release (ESR) version 153.3. Organizations must ensure that all endpoints running affected versions are updated to these patched releases immediately to eliminate the attack vector. Beyond software updates, defense-in-depth measures should be enforced, including enabling strict Content Security Policies to restrict script execution from untrusted sources and ensuring that browser sandboxing features remain active and uncompromised. Additionally, deploying endpoint detection and response solutions capable of monitoring for anomalous memory access patterns or unusual process behavior can provide an additional layer of security against exploitation attempts. Regular vulnerability scanning and penetration testing focused on web application interactions with the browser engine can also help identify similar logical flaws before they are exploited in the wild.