CVE-2022-20449 in Android
Summary
by MITRE • 12/13/2022
In writeApplicationRestrictionsLAr of UserManagerService.java, there is a possible overwrite of system files due to a path traversal error. This could lead to local denial of service with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12 Android-12L Android-13Android ID: A-239701237
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Analysis
by VulDB Data Team • 04/15/2026
The vulnerability identified as CVE-2022-20449 represents a critical path traversal flaw within the Android system's UserManagerService component that specifically affects Android versions 10 through 13. This issue resides in the writeApplicationRestrictionsLAr method of the UserManagerService.java file, where improper input validation allows attackers to manipulate file paths and potentially overwrite critical system files. The vulnerability stems from insufficient sanitization of user-supplied input that gets processed during the application restrictions writing process, creating a scenario where malicious actors can craft specially formatted paths that bypass normal file system access controls. The flaw operates at the core of Android's user management infrastructure, where system-level privileges are required to exploit the vulnerability effectively, making it particularly dangerous in environments where attackers can escalate privileges or have legitimate system access.
The technical implementation of this vulnerability demonstrates a classic path traversal attack vector that leverages the lack of proper path validation in the application restrictions handling mechanism. When the UserManagerService processes application restrictions, it fails to adequately validate or sanitize the paths provided by the input parameters, allowing attackers to manipulate the file system operations through specially crafted inputs. This weakness specifically targets the writeApplicationRestrictionsLAr method, which is responsible for writing application restriction data to persistent storage, and enables attackers to specify arbitrary file paths that could lead to overwriting critical system files or directories. The vulnerability's exploitation requires system execution privileges, indicating that it operates at a privileged level within the Android operating system, and the path traversal occurs during the file writing operation rather than during read operations, making it particularly insidious as it can potentially corrupt system integrity.
The operational impact of CVE-2022-20449 extends beyond simple file overwrites to encompass potential local denial of service conditions that can severely compromise system stability and availability. When exploited successfully, this vulnerability can result in critical system files being overwritten or corrupted, leading to complete system instability or requiring full system reinstallation. The local nature of the attack means that exploitation typically requires an attacker to already have local access to the device, but once achieved, the potential for system-wide disruption is significant. This vulnerability directly impacts Android's user management and application restriction functionality, which are fundamental components for maintaining system security and user isolation. The attack vector's requirement for system execution privileges indicates that it can be exploited by malicious applications or users with elevated permissions, potentially leading to privilege escalation scenarios where attackers can gain deeper system access or manipulate other system components.
Security mitigations for CVE-2022-20449 should focus on implementing robust input validation and path sanitization within the UserManagerService component. The most effective immediate fix involves strengthening the writeApplicationRestrictionsLAr method to properly validate all input paths and ensure that they remain within designated safe directories, preventing traversal outside of intended file system boundaries. Android security patches should implement strict path validation that checks for special characters, directory traversal sequences, and absolute path references that could lead to system file manipulation. Organizations should also consider implementing additional security controls such as mandatory application sandboxing, enhanced privilege controls, and regular system integrity monitoring to detect and prevent exploitation attempts. The vulnerability aligns with CWE-22 Path Traversal and follows ATT&CK technique T1059 Command and Scripting Interpreter, specifically targeting system-level file manipulation. Additionally, this issue reflects broader concerns about input validation in Android system services and represents a critical area where proper security controls should be implemented to prevent unauthorized system file modification and maintain the integrity of the Android security model.