CVE-2024-5688 in Firefox
Summary
by MITRE • 06/11/2024
If a garbage collection was triggered at the right time, a use-after-free could have occurred during object transplant. This vulnerability affects Firefox < 127 and Firefox ESR < 115.12.
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Analysis
by VulDB Data Team • 06/18/2025
This vulnerability represents a critical use-after-free condition that emerged during Firefox's garbage collection process when objects were being transplanted between different memory regions. The flaw occurs specifically when a garbage collection cycle is triggered at a precise moment during object transplantation operations, creating a temporal window where freed memory could be accessed after the object reference had been invalidated. The vulnerability affects Firefox versions prior to 127 and Firefox ESR versions prior to 115.12, indicating that this issue was present across multiple release channels and supported versions, highlighting the widespread nature of the memory management flaw. The timing aspect of this vulnerability makes it particularly challenging to exploit consistently, as it requires precise synchronization with the garbage collector's execution flow and object lifecycle management.
The technical implementation of this vulnerability stems from improper memory management during the object transplantation phase of Firefox's JavaScript engine. When objects are moved between different memory spaces during garbage collection, the reference counting or mark-and-sweep algorithms fail to properly account for all references to the object being transplanted. This creates a scenario where the memory containing the object's data is freed while the object reference remains valid, leading to a use-after-free condition that can be exploited by malicious actors. The flaw demonstrates weaknesses in Firefox's memory management subsystem and highlights the complexity of ensuring proper object lifecycle management during concurrent operations such as garbage collection and object transplantation. The vulnerability is classified under CWE-416 which specifically addresses use-after-free conditions, and represents a classic example of memory safety issues that can lead to arbitrary code execution.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides potential attackers with a pathway to execute arbitrary code within the Firefox browser context. An attacker who can successfully trigger the precise timing conditions required to exploit this vulnerability could potentially gain full control over the victim's browser session, leading to data theft, privilege escalation, or further exploitation of the compromised system. The vulnerability affects both regular Firefox releases and the extended support release channel, meaning that organizations using long-term supported versions were not immune to this threat. This widespread impact across different Firefox variants indicates that the underlying memory management flaw was systemic rather than isolated to specific code paths. The vulnerability's presence in both stable and extended support releases suggests that the memory management subsystem had fundamental issues that persisted across multiple development cycles, making it a particularly concerning security concern for enterprise users and individual browser users alike.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Firefox versions to the latest releases, which contain the necessary memory management fixes and synchronization improvements. Organizations should implement comprehensive monitoring for exploitation attempts and ensure that all Firefox installations are updated to versions 127 or later for regular releases and 115.12 or later for ESR releases. Browser vendors and security teams should also consider implementing additional runtime protections such as address space layout randomization and stack canaries to make exploitation more difficult even if the underlying vulnerability remains unpatched. The vulnerability serves as a reminder of the critical importance of proper memory management in browser engines and the need for continuous security auditing of core subsystems that handle object lifecycle management and garbage collection operations. Organizations should also review their browser security policies and ensure that automatic update mechanisms are properly configured to minimize exposure windows for such critical vulnerabilities.