CVE-2023-5728 in Thunderbird
Summary
by MITRE • 10/25/2023
During garbage collection extra operations were performed on a object that should not be. This could have led to a potentially exploitable crash. This vulnerability affects Firefox < 119, Firefox ESR < 115.4, and Thunderbird < 115.4.1.
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Analysis
by VulDB Data Team • 11/24/2025
The vulnerability identified as CVE-2023-5728 represents a critical memory safety issue within the garbage collection mechanism of Mozilla Firefox and Thunderbird applications. This flaw occurs during the automatic memory management process where the system performs unintended operations on objects that should remain untouched or have already been processed. The improper handling of object references during garbage collection creates a potential pathway for attackers to exploit memory corruption vulnerabilities. The vulnerability specifically impacts versions of Firefox prior to 119, Firefox ESR versions prior to 115.4, and Thunderbird versions prior to 115.4.1, indicating a widespread concern across multiple Mozilla products that rely on similar JavaScript engine components.
The technical nature of this vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, though the specific implementation involves improper object handling during memory cleanup operations. During normal garbage collection cycles, the JavaScript engine attempts to identify and dispose of unused memory objects to optimize resource usage. However, in this case, the system erroneously processes objects that should not be subject to additional operations, potentially leading to memory corruption or arbitrary code execution. The flaw manifests as an inconsistency in the garbage collection algorithm where object lifecycle management becomes compromised, creating opportunities for malicious actors to manipulate the system's memory state through carefully crafted inputs.
The operational impact of CVE-2023-5728 extends beyond simple application instability, as it creates potential for remote code execution when exploited. Attackers could leverage this vulnerability by crafting malicious web content or email messages that trigger the problematic garbage collection path, potentially leading to complete system compromise. The vulnerability's presence in both Firefox and Thunderbird applications means that users are exposed across multiple attack vectors including web browsing, email processing, and potentially file-based attacks. The timing of the flaw during garbage collection operations makes it particularly dangerous as it occurs in the background processes that are often overlooked in security assessments, providing stealthy exploitation opportunities.
Mitigation strategies for this vulnerability require immediate patching of affected software versions to address the core garbage collection logic. System administrators should prioritize updating Firefox, Firefox ESR, and Thunderbird installations to the latest available versions that contain the patched garbage collection implementation. Additionally, organizations should implement network monitoring to detect potential exploitation attempts through unusual memory access patterns or abnormal garbage collection behavior. The vulnerability demonstrates the importance of comprehensive memory safety testing in JavaScript engines and highlights the need for robust input validation and object lifecycle management. Security teams should also consider implementing sandboxing measures and privilege separation to limit the potential impact of successful exploitation attempts, as outlined in the attack techniques documented within the MITRE ATT&CK framework under the system service execution and privilege escalation categories.