CVE-2019-1999 in Android
Summary
by MITRE
In binder_alloc_free_page of binder_alloc.c, there is a possible double free due to improper locking. This could lead to local escalation of privilege in the kernel with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android kernel. Android ID: A-120025196.
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Analysis
by VulDB Data Team • 08/11/2025
The vulnerability identified as CVE-2019-1999 represents a critical double free condition within the Android kernel's binder driver implementation. This flaw exists in the binder_alloc_free_page function located in binder_alloc.c, where inadequate locking mechanisms fail to prevent concurrent access patterns that can result in memory corruption. The binder driver serves as a fundamental component for inter-process communication in Android systems, making this vulnerability particularly dangerous as it operates at the kernel level with elevated privileges. The double free condition occurs when the same memory page is freed twice due to race conditions in the allocation and deallocation process, potentially allowing malicious code to manipulate kernel memory structures.
The technical nature of this vulnerability aligns with CWE-415, which describes improper locking scenarios leading to double free conditions in memory management systems. The flaw exploits a classic race condition where multiple threads or processes can simultaneously access the same memory allocation structures without proper synchronization mechanisms. In the context of the Android kernel, this vulnerability demonstrates how insufficient locking in kernel-space memory management can create pathways for privilege escalation. The binder driver's role in facilitating communication between applications and system services means that exploitation of this vulnerability could potentially allow attackers to gain unauthorized access to system resources and escalate their privileges from user-level to kernel-level execution.
The operational impact of CVE-2019-1999 extends beyond simple local privilege escalation, as it represents a fundamental weakness in Android's security model that can be exploited without requiring any user interaction or additional execution privileges. This characteristic makes the vulnerability particularly concerning from a threat perspective, as it can be automatically exploited by malicious applications installed on the device. The lack of user interaction requirements means that even passive attacks can leverage this vulnerability, potentially allowing attackers to gain root access to devices running affected Android kernel versions. The vulnerability affects all Android kernel implementations that utilize the binder driver for inter-process communication, making it widespread across various Android device models and versions.
Mitigation strategies for CVE-2019-1999 should focus on implementing proper locking mechanisms within the binder driver's memory management functions. The fix requires ensuring that all access to shared memory allocation structures occurs under proper mutex or spinlock protection to prevent concurrent access patterns that lead to double free conditions. Security researchers and device manufacturers should prioritize applying kernel updates that address this specific race condition in binder_alloc.c. The remediation approach should align with ATT&CK technique T1068, which involves exploiting privileges to escalate access, by ensuring that kernel-level memory management functions properly protect against concurrent access patterns. Additionally, system administrators should monitor for any suspicious behavior patterns that might indicate exploitation attempts and implement proper kernel hardening measures to prevent similar vulnerabilities from being introduced in future kernel versions.