CVE-2026-92026 in Firefox
Summary
by MITRE • 09/15/2026
Use-after-free in the Networking component. This vulnerability was fixed in Firefox 156, Firefox ESR 140.16, and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The identified vulnerability represents a critical use-after-free condition within the Mozilla Firefox networking subsystem, specifically affecting components responsible for handling network connections and data transmission protocols. This type of memory management error occurs when an application continues to reference a pointer after the memory it points to has been deallocated or freed by the system. In the context of browser networking stacks, this often involves complex interactions between JavaScript engines, native C++ code, and underlying operating system socket APIs. When a network object is destroyed while still being referenced by another active process or thread within the browser's multi-process architecture, the dangling pointer retains access to memory that may have been reallocated for unrelated purposes. This creates an opportunity for attackers to manipulate program flow or execute arbitrary code with the privileges of the victim user.
From a technical perspective, use-after-free vulnerabilities are particularly dangerous because they can lead to both information disclosure and remote code execution depending on how the freed memory is subsequently utilized. If the attacker can control what data is written into the reallocated memory region before it is accessed again through the dangling pointer, they may be able to craft specific heap layouts that allow for precise memory corruption. This could result in overwriting function pointers or virtual table entries within browser processes such as the content process or network service process. Such exploitation techniques are sophisticated and often require multiple stages of development to bypass modern security mitigations like Address Space Layout Randomization (ASLR) and Heap Spray protections, yet they remain among the most prevalent causes of high-severity vulnerabilities in web browsers due to the complexity of managing dynamic memory across different execution contexts.
The operational impact of this vulnerability is severe, as it potentially allows a remote attacker to execute arbitrary code on the victim's system by tricking them into visiting a maliciously crafted webpage or loading a compromised network resource. Successful exploitation could lead to full compromise of the user environment, including access to sensitive data stored in cookies, local storage, and browser history, as well as potential lateral movement within a corporate network if the browser is used for internal applications. The vulnerability affects multiple versions of Firefox, indicating that it was present across several release cycles before being addressed. This persistence highlights the importance of timely patching strategies and automated update mechanisms to ensure users are protected against known exploits in widely deployed software components.
Industry standards classify this flaw under CWE-416, which defines use-after-free as a situation where an application uses memory after it has been freed, leading to undefined behavior that can be exploited for malicious purposes. In terms of the MITRE ATT&CK framework, this vulnerability aligns with techniques related to initial access and execution, specifically those involving browser-based attacks such as Drive-by Code Execution or Exploitation for Client Execution. Attackers typically leverage these vulnerabilities during targeted campaigns where social engineering is used to direct victims to exploit kits designed to trigger the memory corruption flaw within the networking stack. The presence of this issue in long-term support releases like Firefox ESR underscores the need for rigorous security testing and code review processes, particularly for components that handle untrusted network input over extended periods.
Mitigation strategies primarily involve applying the software updates released by Mozilla Corporation as soon as they become available. Users should ensure their browsers are configured to update automatically or check for updates regularly through the built-in maintenance settings. For enterprise environments, IT administrators must prioritize patching Firefox ESR installations across all endpoints using centralized management tools like Microsoft Endpoint Configuration Manager or other mobile device management solutions that support browser policy enforcement. Additionally, deploying network-level security controls such as web filtering proxies can help block access to known malicious domains and exploit kits before they reach the client machine. While no single mitigation eliminates risk entirely, combining timely patching with defense-in-depth measures significantly reduces the attack surface available to adversaries attempting to leverage this specific memory corruption flaw in Firefox networking components.