CVE-2024-7527 in Firefox
Summary
by MITRE • 08/06/2024
Unexpected marking work at the start of sweeping could have led to a use-after-free. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, and Firefox ESR < 128.1.
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Analysis
by VulDB Data Team • 03/15/2025
The vulnerability identified as CVE-2024-7527 represents a critical use-after-free condition that emerged during the initial phases of sweeping operations within the Firefox browser's memory management system. This flaw manifests when the browser processes certain marking operations at the commencement of garbage collection cycles, creating a scenario where memory locations may be accessed after they have been freed and potentially reallocated. The issue specifically impacts Firefox versions prior to 129, Firefox ESR versions prior to 115.14, and Firefox ESR versions prior to 128.1, indicating a widespread exposure across multiple browser release channels and support cycles. The vulnerability's classification as a use-after-free aligns with CWE-416, which describes the condition where software attempts to access memory after it has been freed, creating potential security risks including arbitrary code execution and system compromise.
The technical implementation of this vulnerability involves the browser's garbage collection mechanism, which is responsible for automatically managing memory allocation and deallocation during web page rendering and script execution. During the sweeping phase of garbage collection, the browser traverses through memory objects to identify and reclaim unused memory. When unexpected marking operations occur at the beginning of this process, the system may prematurely free memory objects while still references to them exist within the marking algorithm. This creates a race condition where freed memory locations can be accessed by subsequent operations, potentially allowing malicious actors to manipulate the browser's memory state and execute unauthorized code. The flaw is particularly concerning because it occurs during fundamental browser operations that are continuously executed during normal browsing sessions.
The operational impact of CVE-2024-7527 extends beyond simple browser instability, presenting significant security risks that could be exploited by threat actors. A successful exploitation could enable attackers to execute arbitrary code with the privileges of the browser process, potentially leading to complete system compromise. The vulnerability's presence in both regular Firefox releases and extended support releases means that organizations with legacy systems or those unable to immediately upgrade face prolonged exposure. This risk is compounded by the fact that the vulnerability can be triggered through normal web browsing activities, making it particularly dangerous as it does not require specialized attack vectors or user interaction beyond visiting compromised websites. The ATT&CK framework categorizes this type of vulnerability under T1059.007 for Windows Command Shell and T1566 for Phishing, as attackers could leverage such memory corruption flaws to establish persistent access or deliver malware payloads through compromised web content.
Mitigation strategies for CVE-2024-7527 primarily focus on immediate version upgrades to patched browser releases, which address the underlying memory management flaw through corrected garbage collection algorithms and improved memory access controls. Organizations should prioritize updating Firefox installations to versions 129, 115.14, or 128.1 respectively, depending on their current release channel. Additionally, implementing browser hardening measures such as enabling sandboxing features, restricting JavaScript execution in sensitive contexts, and deploying web application firewalls can provide additional protective layers. Network-level mitigations including content filtering and intrusion detection systems can help identify and block exploitation attempts targeting this vulnerability. Security teams should also monitor for indicators of compromise related to memory corruption exploits and maintain updated threat intelligence feeds to detect potential exploitation attempts. The remediation process should include comprehensive testing of patched versions to ensure compatibility with existing browser extensions and enterprise security tools while maintaining the integrity of the browser's security model.