CVE-2019-2126 in Android
Summary
by MITRE
In ParseContentEncodingEntry of mkvparser.cc, there is a possible double free due to a missing reset of a freed pointer. This could lead to remote code execution with no additional execution privileges needed. User interaction is needed for exploitation. Product: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-127702368.
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Analysis
by VulDB Data Team • 05/21/2025
The vulnerability identified as CVE-2019-2126 represents a critical memory safety issue within the Matroska media file parser component of Android systems. This flaw exists in the ParseContentEncodingEntry function located in the mkvparser.cc source file, where a double free condition can occur due to improper pointer management. The vulnerability stems from a missing reset operation on a freed memory pointer, creating a scenario where the same memory location can be deallocated twice, potentially leading to unpredictable behavior and system instability. The issue affects multiple Android versions including 7.0, 7.1.1, 7.1.2, 8.0, 8.1, and 9, indicating a widespread impact across the Android ecosystem. According to CWE-415, this vulnerability classifies as a double free condition, which is a well-documented memory corruption vulnerability that can be exploited to execute arbitrary code. The ATT&CK framework categorizes this under privilege escalation and code execution techniques, as the vulnerability can be leveraged for remote code execution without requiring additional privileges. The exploitation requires user interaction, typically through the malicious media file being opened or processed by an application that utilizes the affected parser component.
The operational impact of this vulnerability extends beyond simple system crashes or instability, as it creates a potential pathway for remote code execution attacks. When a maliciously crafted Matroska file is processed by an Android application that employs the vulnerable mkvparser library, the double free condition can be triggered during content encoding entry parsing. This memory corruption can be manipulated by attackers to overwrite critical memory structures, potentially allowing them to redirect program execution flow or inject malicious code. The vulnerability's remote execution capability means that attackers can deliver malicious content through various channels such as email attachments, web downloads, or media sharing platforms without requiring physical access to the target device. The absence of additional privilege requirements makes this vulnerability particularly dangerous as it can be exploited by adversaries with minimal attack surface. The specific nature of the vulnerability in mkvparser.cc suggests that it affects applications handling Matroska format media files, which includes media players, video streaming applications, and other multimedia processing software.
Mitigation strategies for CVE-2019-2126 must address both immediate patching requirements and broader security hardening measures. Android device manufacturers and developers should prioritize applying the official security patches released by Google to address this memory corruption vulnerability. The patching process should include thorough regression testing to ensure that the fix does not introduce compatibility issues with legitimate media files or applications. Security researchers should implement memory safety checks and pointer validation mechanisms within the affected codebase to prevent similar issues in future development cycles. Input validation for media file parsing should be strengthened to detect and reject malformed or malicious content before it reaches the vulnerable parsing functions. Organizations should also consider implementing application sandboxing and memory protection mechanisms such as address space layout randomization and stack canaries to reduce the exploitability of similar vulnerabilities. Network-based defenses can include content filtering and media file scanning to prevent malicious Matroska files from reaching end users. Additionally, developers should follow secure coding practices such as the CERT C Secure Coding Standard recommendations for memory management and pointer handling, particularly focusing on preventing use-after-free and double free conditions. The vulnerability serves as a reminder of the critical importance of memory safety in multimedia processing libraries, where improper pointer management can have severe security implications for end-user systems.