CVE-2023-21111 in Android
Summary
by MITRE • 05/16/2023
In several functions of PhoneAccountRegistrar.java, there is a possible way to prevent an access to emergency services due to improper input validation. This could lead to local 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-256819769
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Analysis
by VulDB Data Team • 09/13/2025
The vulnerability identified as CVE-2023-21111 resides within the PhoneAccountRegistrar.java component of Android operating systems spanning versions 11 through 13, including Android 12, 12L, and 13. This flaw represents a critical security issue that could potentially disrupt emergency services accessibility, fundamentally compromising the system's reliability and user safety. The vulnerability manifests in multiple functions of the PhoneAccountRegistrar class, where inadequate input validation creates exploitable conditions that could prevent proper access to emergency services.
The technical root cause of this vulnerability stems from improper validation mechanisms within the phone account registration process. When the system processes phone account registrations, it fails to adequately validate input parameters that govern emergency service access. This validation gap allows malicious actors or system errors to manipulate the registration flow in ways that could block emergency service functionality. The flaw specifically affects how the system handles emergency service routing and account registration, creating potential pathways where legitimate emergency calls could be intercepted or blocked entirely.
This vulnerability presents a significant operational impact as it could lead to local denial of service conditions without requiring any special execution privileges or user interaction for exploitation. The implications extend beyond simple service disruption since emergency services are critical infrastructure components that must remain accessible at all times. The vulnerability's nature means that any local process or application with access to the phone account registration system could potentially exploit this weakness to prevent emergency calls from being properly routed, thereby creating a serious safety hazard for users.
From a cybersecurity perspective, this vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness that can lead to various security issues including denial of service conditions. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and denial of service tactics, where attackers can manipulate system components to prevent legitimate services from functioning properly. The lack of user interaction requirement makes this particularly concerning as it can be exploited automatically without any manual intervention from the end user.
The mitigation strategy for this vulnerability requires immediate patching of affected Android versions through official security updates provided by Google. Organizations and users should prioritize applying these updates as soon as they become available to prevent exploitation. Additionally, system administrators should implement monitoring procedures to detect any unusual patterns in phone account registration or emergency service access that might indicate exploitation attempts. The fix typically involves strengthening input validation mechanisms within the PhoneAccountRegistrar.java file to ensure that all phone account registration parameters are properly validated before being processed, thereby preventing malicious or malformed inputs from disrupting emergency service functionality.