CVE-2017-7752 in Firefox
Summary
by MITRE
A use-after-free vulnerability during specific user interactions with the input method editor (IME) in some languages due to how events are handled. This results in a potentially exploitable crash but would require specific user interaction to trigger. 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-2017-7752 represents a critical use-after-free flaw within the input method editor functionality of Mozilla Firefox and Thunderbird applications. This security weakness manifests specifically during user interactions with IME components in certain languages, where improper event handling creates conditions that allow memory corruption to occur. The vulnerability stems from the improper management of memory resources when processing input method editor events, creating opportunities for malicious actors to exploit the application's memory management routines.
The technical implementation of this flaw involves the application's failure to properly validate or manage memory references during IME event processing. When users interact with input method editors in supported languages, the application's event handling mechanism attempts to access memory locations that have already been freed or reallocated. This use-after-free condition occurs because the system does not adequately verify that referenced memory blocks remain valid before accessing them, creating a scenario where an attacker could potentially manipulate the application's memory state to execute arbitrary code. The vulnerability is particularly concerning because it requires only specific user interaction to trigger, making it exploitable in real-world scenarios without requiring elevated privileges or complex attack vectors.
The operational impact of CVE-2017-7752 extends beyond simple application instability, as the use-after-free condition can result in complete system compromise when successfully exploited. Attackers can leverage this vulnerability to execute malicious code with the privileges of the affected application, potentially leading to full system compromise or data exfiltration. The vulnerability affects widely used applications including Firefox versions prior to 54, Firefox ESR versions prior to 52.2, and Thunderbird versions prior to 52.2, representing significant exposure across enterprise and individual user environments. This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and corresponds to attack patterns within the ATT&CK framework that involve memory corruption exploitation techniques.
Organizations and users affected by this vulnerability should immediately implement mitigations through patch management and application updates to address the underlying memory management issues. The most effective remediation involves upgrading to patched versions of Firefox, Firefox ESR, and Thunderbird that contain proper memory validation and event handling routines. Additional protective measures include implementing application sandboxing, monitoring for unusual memory access patterns, and conducting regular security assessments of affected applications. Security teams should also consider deploying intrusion detection systems capable of identifying exploitation attempts targeting memory corruption vulnerabilities, while ensuring that user interaction with potentially vulnerable applications is minimized until full patches are deployed. The vulnerability demonstrates the critical importance of proper memory management in complex applications and highlights the need for continuous security testing of input processing components.