CVE-2023-20928 in Android
Summary
by MITRE • 01/26/2023
In binder_vma_close of binder.c, there is a possible use after free due to improper locking. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-254837884References: Upstream kernel
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Analysis
by VulDB Data Team • 09/04/2025
The vulnerability identified as CVE-2023-20928 resides within the Android kernel's binder driver implementation, specifically in the binder_vma_close function. This flaw represents a critical security weakness that could enable local privilege escalation without requiring any additional execution privileges or user interaction for exploitation. The vulnerability manifests as a use-after-free condition that stems from inadequate locking mechanisms within the kernel's memory management subsystem. The binder driver serves as a crucial component for inter-process communication in Android systems, making this vulnerability particularly concerning as it could be leveraged to gain elevated system privileges.
The technical root cause of this vulnerability lies in the improper synchronization mechanisms within the binder_vma_close function of the binder.c source file. When a virtual memory area is being closed, the function fails to maintain proper locking protocols that would prevent concurrent access to freed memory regions. This race condition allows an attacker to potentially access memory that has already been deallocated, creating opportunities for memory corruption and arbitrary code execution. The flaw specifically impacts the Android kernel's memory management and virtual memory subsystem, where the lack of adequate mutex or spinlock protection during the cleanup process creates a window for exploitation. This type of vulnerability aligns with CWE-416, which describes use-after-free conditions, and represents a classic example of improper lock management in kernel space.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally compromises the security model of Android systems. An attacker with local access could leverage this flaw to elevate their privileges from a regular user context to system-level access, potentially gaining complete control over the device. This could enable unauthorized access to sensitive data, modification of system files, installation of malicious applications, and complete compromise of the device's security posture. The vulnerability's exploitation requires no user interaction, making it particularly dangerous as it can be triggered automatically without any deliberate action from the user. The implications are severe for mobile devices, IoT systems, and any platform relying on Android's kernel-level communication mechanisms.
Mitigation strategies for CVE-2023-20928 should focus on implementing proper locking mechanisms within the binder driver's memory management functions. The most effective approach involves adding appropriate mutex or spinlock protection around the memory deallocation and cleanup operations in the binder_vma_close function to prevent concurrent access to freed memory regions. Security patches should ensure that all memory management operations maintain proper synchronization protocols to eliminate the race condition that enables the use-after-free scenario. Additionally, system administrators should implement regular kernel updates and apply security patches immediately upon availability. The vulnerability's classification as a local privilege escalation issue also suggests implementing additional runtime protections such as kernel address space layout randomization and stack canaries to further complicate exploitation attempts. Organizations should also consider monitoring for suspicious memory access patterns and implementing automated patch management systems to ensure timely remediation of such critical vulnerabilities.