CVE-2026-109713 in Firefox
Summary
by MITRE • 10/13/2026
Use-after-free in the Crash Reporting component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.
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Analysis
by VulDB Data Team • 10/13/2026
The identified vulnerability represents a critical memory management error classified as an out-of-bounds write, specifically manifesting as a use-after-free condition within the crash reporting subsystem of Mozilla Firefox browsers. This flaw arises when the application attempts to access or manipulate memory that has already been deallocated by the system's garbage collector or explicit cleanup routines. In the context of browser architecture, components such as crash reporters often operate with elevated privileges and handle sensitive diagnostic data, making them attractive targets for exploitation. The root cause typically involves a race condition or logic error where a pointer to an object remains valid in one part of the code while that same memory region is freed elsewhere, leading to dangling pointers being dereferenced during subsequent operations.
From a technical perspective, this vulnerability falls under Common Weakness Enumeration category CWE-416, which describes using a pointer after it has been freed. When exploited, an attacker can craft malicious web content or trigger specific browser states that cause the crash reporter to write data into memory locations controlled by the attacker rather than the intended buffer structure. This out-of-bounds write capability allows for arbitrary code execution with the privileges of the user running the browser process. The impact is severe because it bypasses many modern security mitigations such as heap randomization and can lead to full system compromise if combined with other vulnerabilities or through direct exploitation techniques that achieve kernel-level access via sandbox escape mechanisms.
The operational impact extends beyond simple application crashes, which are often associated with memory errors in less critical components. In this case, the crash reporting module is designed to capture detailed state information before termination, meaning it may hold references to various internal objects and buffers. An attacker leveraging this flaw could potentially read sensitive user data stored in adjacent memory regions or overwrite function pointers within virtual tables, thereby redirecting program execution flow. This aligns with MITRE ATT&CK technique T1203, which covers exploitation for client-side code execution, indicating that the vulnerability is primarily targeted at end-user systems rather than server infrastructure.
Mitigation strategies focus on ensuring timely patch deployment and reinforcing memory safety practices within browser development lifecycles. The definitive resolution was implemented in Firefox version 158 and Firefox Extended Support Release (ESR) version 153.5, where developers corrected the lifecycle management of objects involved in crash reporting to prevent access after deallocation. Organizations should prioritize updating all endpoints running affected versions immediately to close this attack vector. Additionally, enabling automatic updates ensures that future patches for similar memory safety issues are applied without manual intervention. Security teams should also monitor for indicators of compromise related to unusual network activity from browser processes or unexpected crashes in diagnostic tools, which may signal attempted exploitation attempts against unpatched systems.