CVE-2023-20959 in Android
Summary
by MITRE • 03/24/2023
In AddSupervisedUserActivity, guest users are not prevented from starting the activity due to missing permissions checks. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-13Android ID: A-249057848
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Analysis
by VulDB Data Team • 09/06/2025
The vulnerability identified as CVE-2023-20959 resides within the Android operating system's AddSupervisedUserActivity component, representing a critical privilege escalation flaw that affects Android 13. This issue stems from insufficient permission validation mechanisms that fail to properly restrict guest user access to supervised user activity initiation. The vulnerability operates at the system level where proper access controls should prevent unauthorized users from executing privileged operations. According to the Android security framework, this represents a failure in the mandatory access control (MAC) mechanisms that should enforce user role-based permissions. The flaw allows any user account, regardless of their privilege level or guest status, to bypass normal authentication and authorization checks required for supervised user activities.
The technical implementation of this vulnerability demonstrates a classic missing permission check scenario where the system fails to validate whether the initiating user possesses the necessary credentials or privileges to execute the AddSupervisedUserActivity function. This type of flaw typically maps to CWE-284, which describes improper access control where an actor can perform operations they should not be permitted to execute. The vulnerability operates through a privilege escalation vector that does not require any additional execution privileges or user interaction, making it particularly dangerous as it can be exploited automatically by any local process or user. The absence of proper access control validation in the Android framework's user management subsystem creates an exploitable gap in the system's security model.
The operational impact of this vulnerability extends beyond simple unauthorized access to represent a significant threat to Android device security and user privacy. Local privilege escalation attacks leveraging this flaw could enable malicious actors to gain elevated system privileges without requiring additional malicious payloads or user interaction. This capability allows attackers to potentially modify system configurations, access restricted data, or escalate their privileges to full administrative control. The vulnerability's exploitation does not require user interaction, which means it can be triggered automatically by background processes or malicious applications that are already running with local access. This characteristic aligns with ATT&CK technique T1068, which describes local privilege escalation through exploitation of system vulnerabilities. The flaw essentially provides a backdoor mechanism that bypasses normal Android security boundaries and user role enforcement.
Mitigation strategies for CVE-2023-20959 should focus on immediate system updates and patch deployment through the Android security update cycle. Organizations should implement comprehensive monitoring for unauthorized supervised user activity initiation attempts and establish baseline behavioral patterns for system access. The Android security model requires that all system components implementing user management functions must perform strict permission validation before allowing any privileged operations. This vulnerability highlights the importance of the principle of least privilege enforcement in mobile operating systems and demonstrates why proper access control implementation is critical for maintaining system integrity. Security teams should also consider implementing additional runtime monitoring to detect unusual patterns of supervised user activity initiation that could indicate exploitation attempts. The fix for this vulnerability would typically involve strengthening the permission checking mechanism within the AddSupervisedUserActivity function to ensure that only properly authenticated and authorized users can initiate supervised user activities, thereby preventing guest users from bypassing normal access controls.