CVE-2026-117878 in Firefox
Summary
by MITRE • 10/27/2026
Other issue, use-after-free in the Storage: IndexedDB component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/27/2026
The identified vulnerability represents a critical memory management error within Mozilla's storage subsystem, specifically affecting the IndexedDB implementation. As a use-after-free flaw, this defect occurs when the application attempts to access memory that has already been deallocated by the system or garbage collector. In the context of web browsers, such vulnerabilities are particularly dangerous because they reside in components responsible for handling persistent client-side data storage, which is frequently accessed during complex web interactions involving databases and asynchronous operations. The root cause typically involves a mismatch between object lifetime management and pointer validity checks, allowing an attacker to manipulate references to freed memory regions before the system reclaims them or assigns them to new objects.
From a technical perspective, this flaw falls under the Common Weakness Enumeration category CWE-416, which defines use-after-free conditions where pointers are used after they have been invalidated. The operational impact of such a vulnerability is severe, as it can lead to arbitrary code execution with the privileges of the user running the browser. An attacker could craft a malicious web page that triggers specific IndexedDB operations designed to exploit this race condition or logic error. By carefully controlling the timing and content of database transactions, an adversary might overwrite freed memory structures with controlled data, thereby hijacking control flow when the application subsequently attempts to use these corrupted pointers. This can result in full system compromise, allowing for data exfiltration, installation of malware, or further lateral movement within a networked environment.
This type of vulnerability aligns with several techniques observed in real-world attacks as documented by the MITRE ATT&CK framework. Specifically, it relates to memory corruption exploitation strategies often categorized under execution and privilege escalation tactics. Attackers frequently leverage use-after-free bugs to bypass modern browser security mitigations such as heap spraying protections or control flow integrity mechanisms. The persistence of this issue across multiple versions indicates a systemic challenge in the lifecycle management of IndexedDB objects, particularly during asynchronous cleanup processes where memory is freed while background tasks may still hold references to those same objects.
Mitigation for this vulnerability relies primarily on software updates provided by Mozilla. Users and administrators must ensure that Firefox version 159 or later is installed, along with any applicable Extended Support Release (ESR) versions such as ESR 115.44 or ESR 153.6. These releases contain the necessary patches to correct the memory management logic within the IndexedDB component. For organizations managing large fleets of browsers, automated patching mechanisms should be employed to ensure timely deployment of these fixes. Additionally, defense-in-depth strategies such as enabling strict Content Security Policies and utilizing browser hardening configurations can help mitigate the potential impact by restricting the types of scripts that can interact with storage APIs, thereby reducing the attack surface available for exploitation attempts.