CVE-2023-21087 in Android
Summary
by MITRE • 04/19/2023
In PreferencesHelper.java, an uncaught exception may cause the device to get stuck in a boot loop. This could lead to local persistent denial of service with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-12 Android-12L Android-13Android ID: A-261723753
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Analysis
by VulDB Data Team • 09/10/2025
The vulnerability described in CVE-2023-21087 represents a critical boot loop condition within the Android operating system's preference handling mechanism. This issue resides in the PreferencesHelper.java component which manages application and system preferences during the device boot process. The flaw manifests when an unhandled exception occurs during preference processing, creating a scenario where the system cannot properly initialize its configuration settings and subsequently enters an infinite reboot cycle. The vulnerability affects multiple Android versions including Android 11, 12, 12L, and 13, indicating it is a widespread issue that has persisted across several major releases of the mobile operating system.
The technical nature of this vulnerability stems from inadequate exception handling within the preference management subsystem. When the system attempts to process user or system preferences during boot initialization, if an exception occurs that is not properly caught and handled, the preference processing component fails to complete its initialization sequence. This failure prevents the system from proceeding with normal boot operations and instead triggers a restart mechanism that continuously attempts to initialize the same problematic preference component, resulting in the characteristic boot loop behavior. The flaw operates at a low system level within the Android framework, making it particularly dangerous as it can affect the fundamental boot process of the device.
The operational impact of this vulnerability is severe and persistent, as it creates a local denial of service condition that requires physical device intervention to resolve. Once exploited, the device becomes completely unusable as it continuously reboots without ever reaching the normal operating system state. The attack vector is particularly concerning because it requires no user interaction or additional privileges, making it easily exploitable through automated means. This vulnerability can be triggered by malformed preference data, corrupted preference files, or other conditions that cause the preference processing component to throw unhandled exceptions. The persistent nature of the issue means that even after the triggering condition is removed, the device will continue to boot loop until manual intervention occurs through recovery mode or factory resets.
The vulnerability aligns with CWE-459, which describes incomplete cleanup issues in software systems, and represents a classic example of a system initialization failure that can lead to complete system unavailability. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers system shutdown/reboot attacks, and demonstrates how low-level operating system components can be leveraged to create persistent denial of service conditions. Organizations and users should implement immediate mitigations including applying the latest security patches from their device manufacturers, monitoring for unusual boot behavior, and maintaining recovery procedures for affected devices. The vulnerability underscores the critical importance of robust exception handling in system-level components and highlights the need for comprehensive testing of boot processes under various failure conditions to prevent similar issues from compromising device availability and user access to critical mobile services.