CVE-2026-117964 in Firefox
Summary
by MITRE • 10/27/2026
Use-after-free in the Panning and Zooming component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
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 browser's Panning and Zooming subsystem. This component is responsible for handling user interactions related to viewport manipulation, including touch gestures and mouse wheel events that adjust the scale or position of web content. The core technical flaw arises when the application fails to properly manage the lifecycle of internal objects associated with these interaction states. Specifically, a pointer to an object remains valid in memory after the underlying data structure has been deallocated or freed due to premature cleanup logic during rapid state transitions. When subsequent operations attempt to access this dangling pointer under specific timing conditions triggered by user input, the application writes to invalid memory addresses rather than crashing immediately, leading to potential heap corruption.
From a security architecture perspective, this flaw aligns with CWE-416, which describes use-after-free vulnerabilities where software continues to use a pointer after it has been freed. The operational impact of such a vulnerability is severe because modern browsers execute untrusted web content from various origins. An attacker could craft a malicious webpage that triggers the specific sequence of panning or zooming actions required to exploit this race condition. By carefully controlling memory allocation patterns, an adversary might achieve arbitrary code execution with the privileges of the victim user. This effectively bypasses standard browser sandboxing mechanisms if the heap corruption allows for control over critical function pointers or object vtables within the rendering engine. The vulnerability was addressed in Firefox version 159 and Firefox Extended Support Release (ESR) version 153.6, where developers implemented stricter checks to ensure that objects are not accessed after their designated scope ends during viewport updates.
In terms of threat modeling and attack vectors, this type of memory corruption is often associated with advanced persistent threats or sophisticated drive-by download campaigns. According to the MITRE ATT&CK framework, such vulnerabilities facilitate initial access through exploitation techniques categorized under software vulnerability exploitation. Attackers typically rely on social engineering to lure users into visiting compromised sites that contain exploit code designed to trigger the use-after-free condition. The lack of immediate crash behavior in some instances makes detection difficult for standard security monitoring tools, as the browser may appear stable while memory structures are being manipulated behind the scenes. This stealth characteristic increases the risk of successful exploitation before defensive measures can react.
Mitigation strategies primarily involve ensuring that all client systems running Firefox or its ESR variant are updated to the patched versions mentioned above. For organizations managing large fleets of endpoints, automated patch management solutions should be configured to prioritize this update due to the high severity associated with memory corruption vulnerabilities in web browsers. Additionally, security teams can employ browser hardening techniques such as disabling JavaScript execution on untrusted domains or utilizing content security policies that restrict inline scripts and external resource loading where feasible. While these controls do not directly fix the underlying code flaw, they reduce the attack surface by limiting the ability of malicious scripts to execute complex memory manipulation routines required for successful exploitation. Continuous monitoring for anomalous browser behavior and keeping threat intelligence feeds updated regarding known exploit kits targeting this specific component will further enhance defensive posture against potential attempts leveraging this vulnerability.