CVE-2023-21052 in Android
Summary
by MITRE • 03/24/2023
In setToExternal of ril_external_client.cpp, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-259063189References: N/A
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Analysis
by VulDB Data Team • 09/09/2025
The vulnerability identified as CVE-2023-21052 resides within the Android kernel's ril_external_client.cpp implementation, specifically in the setToExternal function where a critical out-of-bounds write condition exists due to inadequate bounds checking mechanisms. This flaw represents a significant security weakness that could potentially allow malicious actors to escalate privileges locally within the system. The vulnerability manifests when the system processes external client requests through the RIL (Radio Interface Layer) component, which serves as the interface between the cellular modem and the Android framework. The missing bounds check in the setToExternal function creates an opportunity for attackers to write data beyond the allocated memory boundaries, potentially corrupting adjacent memory regions and undermining system stability.
The technical nature of this vulnerability aligns with CWE-787, which describes out-of-bounds write conditions that occur when a program writes to memory locations beyond the bounds of a buffer. This particular implementation flaw exists within the radio interface layer where external client communications are handled, making it a prime target for privilege escalation attacks. The vulnerability requires system execution privileges for exploitation, indicating that while it doesn't necessitate user interaction, it still demands that an attacker already possesses some level of system access or can achieve a foothold within the system environment. The Android ID A-259063189 further emphasizes the severity and classification of this issue within the Android security framework.
From an operational impact perspective, this vulnerability could enable attackers to gain elevated privileges within the Android system, potentially allowing them to execute arbitrary code with system-level permissions. The local escalation of privilege means that an attacker who has already gained some level of access to the device could leverage this flaw to move from a regular user context to a system-level privileged context. This could result in complete system compromise, allowing unauthorized access to sensitive data, modification of system files, and potential persistence mechanisms. The implications extend beyond simple privilege escalation as this could enable attackers to manipulate cellular communications, access secure storage areas, or interfere with critical system functions that depend on the RIL interface.
Mitigation strategies for CVE-2023-21052 should focus on implementing proper bounds checking mechanisms within the setToExternal function and ensuring that all buffer operations include adequate validation before memory writes occur. System administrators and device manufacturers should prioritize applying security patches and updates that address this specific vulnerability in the Android kernel. The implementation should follow established security practices such as those outlined in the OWASP Secure Coding Guidelines and the CERT Secure Coding Standards, which emphasize the importance of input validation and memory safety. Additionally, runtime protections such as stack canaries, address space layout randomization, and memory protection mechanisms should be enabled to provide additional layers of defense against exploitation attempts. Regular security assessments and code reviews focusing on buffer management and memory operations should be conducted to identify and remediate similar vulnerabilities across the Android kernel implementation.