CVE-2019-11752 in Firefox
Summary
by MITRE
It is possible to delete an IndexedDB key value and subsequently try to extract it during conversion. This results in a use-after-free and a potentially exploitable crash. This vulnerability affects Firefox < 69, Thunderbird < 68.1, Thunderbird < 60.9, Firefox ESR < 60.9, and Firefox ESR < 68.1.
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Analysis
by VulDB Data Team • 11/26/2025
This vulnerability represents a critical use-after-free condition in Mozilla Firefox and Thunderbird applications that stems from improper handling of IndexedDB key value operations during data conversion processes. The flaw occurs when an application attempts to delete an IndexedDB key value and subsequently tries to extract that same value during a conversion operation, creating a scenario where freed memory is accessed. This type of vulnerability falls under the CWE-416 category of Use After Free, which is classified as a serious memory safety issue that can lead to arbitrary code execution. The vulnerability affects multiple Mozilla products including Firefox versions prior to 69, Thunderbird versions prior to 68.1 and 60.9, as well as their respective ESR (Extended Support Release) versions, indicating a widespread impact across the browser and email client ecosystem.
The technical exploitation of this vulnerability involves a specific sequence of operations that triggers memory management issues within the browser's IndexedDB implementation. When a key value is deleted from the IndexedDB storage system, the memory associated with that value is freed from the application's heap. However, during the subsequent data conversion process, the application attempts to access this already freed memory location, resulting in undefined behavior that can manifest as crashes or potentially allow remote code execution. This memory corruption scenario creates opportunities for attackers to craft malicious web content that can trigger the vulnerable code path, leading to system compromise. The vulnerability demonstrates the complexity of memory management in modern web browsers where multiple components must coordinate properly to prevent such dangerous conditions.
The operational impact of this vulnerability extends beyond simple application crashes to potentially enable full system compromise through remote code execution. Attackers can leverage this vulnerability by hosting malicious web content that forces the browser into the vulnerable code path, particularly when users visit compromised websites or open malicious email attachments in Thunderbird. The exploitation requires the victim to interact with the malicious content, making this a client-side attack vector that can be delivered through various means including phishing campaigns, drive-by downloads, or compromised websites. The vulnerability's presence in both regular and ESR versions indicates that organizations running older supported releases are at risk, potentially requiring urgent patch management strategies. This type of vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, where the exploitation could enable attackers to execute arbitrary commands on the victim's system.
Mitigation strategies for this vulnerability require immediate patching of affected software versions to address the root cause in the IndexedDB implementation. Organizations should prioritize updating Firefox and Thunderbird installations to versions 69, 68.1, 60.9, and their respective ESR releases where the vulnerability has been resolved. System administrators should implement automated patch management solutions to ensure all endpoints receive updates promptly. Additional protective measures include configuring browser security settings to restrict IndexedDB access, implementing web application firewalls, and monitoring for suspicious network activity that might indicate exploitation attempts. The vulnerability demonstrates the importance of memory safety practices in browser development and highlights the need for comprehensive testing of edge cases in data management operations. Organizations should also consider implementing user education programs to help identify and avoid potentially malicious web content that could trigger such vulnerabilities.