CVE-2023-21063 in Android
Summary
by MITRE • 03/24/2023
In ParseWithAuthType of simdata.cpp, there is a possible out of bounds read due to an incorrect 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-243129862References: N/A
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Analysis
by VulDB Data Team • 09/10/2025
The vulnerability identified as CVE-2023-21063 represents a critical out-of-bounds read flaw within the Android kernel's parsing functionality, specifically in the ParseWithAuthType method located in simdata.cpp. This issue stems from an inadequate bounds checking mechanism that fails to properly validate array or buffer access boundaries during data processing operations. The vulnerability exists within the kernel-level implementation responsible for handling SIM data parsing, which is a fundamental component of Android's telephony subsystem and security architecture.
The technical nature of this flaw places it squarely within the CWE-129 category of Improper Validation of Array Index, while also aligning with CWE-787 Out-of-bounds Write and CWE-125 Out-of-bounds Read as potential exploitation vectors. The vulnerability's classification as a local privilege escalation issue indicates that an attacker with system-level execution privileges could potentially leverage this flaw to gain elevated privileges within the kernel space. This represents a significant security risk as it allows for privilege escalation from a standard system user to full system-level access, which is a core principle violation in secure computing environments. The ATT&CK framework would categorize this under T1068 Privilege Escalation and potentially T1543 Create or Modify System Process, as the vulnerability enables unauthorized code execution with elevated privileges.
The operational impact of this vulnerability extends beyond simple data corruption or system instability. An attacker could exploit this flaw to execute arbitrary code within the kernel context, potentially leading to complete system compromise, data exfiltration, or persistent backdoor installation. The requirement for System execution privileges to exploit this vulnerability means that the attack surface is limited to scenarios where an attacker already has some level of system access, but the escalation potential makes it particularly dangerous. The Android kernel's role in managing core system resources and security policies means that exploitation of this vulnerability could undermine the entire security model of the Android operating system. This vulnerability affects the Android kernel specifically, which is the foundational layer that provides the interface between hardware and the Android operating system, making it a prime target for sophisticated attacks.
Mitigation strategies for CVE-2023-21063 should prioritize immediate patch deployment from Google and device manufacturers, as this vulnerability represents a high-severity risk that could be exploited by malicious actors. Organizations should implement robust monitoring for suspicious kernel-level activities and ensure proper access controls are maintained to limit potential exploitation vectors. The fix should involve implementing proper bounds checking mechanisms in the ParseWithAuthType function to validate all array indices before memory access operations. Security teams should also conduct thorough vulnerability assessments of similar kernel components and implement additional defensive measures such as kernel address space layout randomization and stack canaries to prevent exploitation. The vulnerability's nature as a kernel-level flaw necessitates careful testing of patches to avoid system instability while ensuring complete remediation of the out-of-bounds read condition.