CVE-2017-7757 in Firefox
Summary
by MITRE
A use-after-free vulnerability in IndexedDB when one of its objects is destroyed in memory while a method on it is still being executed. This results in a potentially exploitable crash. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-7757 represents a critical use-after-free condition within Firefox's IndexedDB implementation, a client-side storage mechanism that allows web applications to store and retrieve data locally. This flaw occurs when an IndexedDB object is prematurely deallocated from memory while an active method or function is still executing on that object, creating a scenario where subsequent operations may attempt to access freed memory locations. The technical nature of this vulnerability places it squarely within the realm of memory safety issues that can lead to arbitrary code execution, making it particularly dangerous for browser environments where untrusted code execution is a primary concern.
The operational impact of this vulnerability extends beyond simple crash conditions to potentially enable remote code execution attacks. When an attacker can manipulate the timing of object destruction and method execution, they may be able to corrupt memory in ways that allow them to inject and execute malicious code within the browser's security context. This represents a classic use-after-free exploit pattern where the freed memory can be reallocated for attacker-controlled data, leading to control flow hijacking. The vulnerability specifically affects Firefox versions prior to 54, Firefox ESR versions prior to 52.2, and Thunderbird versions prior to 52.2, indicating that the flaw existed in the IndexedDB implementation across multiple Mozilla products. The exploitation of this vulnerability requires careful timing and memory manipulation, typically falling under the attack techniques documented in the MITRE ATT&CK framework under the 'Exploitation for Client Execution' tactic.
From a security standards perspective, this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in memory management, and represents a critical flaw in the browser's memory safety mechanisms. The IndexedDB implementation's failure to properly manage object lifecycle during concurrent method execution demonstrates a fundamental flaw in resource management that violates basic security principles. Organizations and users affected by this vulnerability should immediately upgrade to patched versions of Firefox, Firefox ESR, and Thunderbird to mitigate the risk of exploitation. The remediation process involves not only updating software but also implementing monitoring for potential exploitation attempts, as the crash conditions may be leveraged as part of broader attack campaigns targeting browser environments. This vulnerability underscores the importance of rigorous memory safety testing and the critical need for proper object lifecycle management in complex software systems, particularly those handling untrusted input data.