CVE-2023-21078 in Android
Summary
by MITRE • 03/24/2023
In rtt_unpack_xtlv_cbfn of dhd_rtt.c, there is a possible out of bounds write due to a buffer overflow. 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-254840211References: N/A
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Analysis
by VulDB Data Team • 09/10/2025
The vulnerability identified as CVE-2023-21078 represents a critical buffer overflow condition within the Android kernel's real-time transport protocol implementation. This flaw exists in the rtt_unpack_xtlv_cbfn function located in the dhd_rtt.c file, which is part of the Broadcom driver for wireless networking components. The vulnerability stems from inadequate bounds checking during the processing of extended type-length-value (XTLV) structures used in RTT (Real-Time Transport) communication protocols. The flaw allows an attacker to potentially write data beyond the allocated memory boundaries, creating opportunities for arbitrary code execution within the kernel space.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking permits writing beyond allocated buffer limits. This specific implementation flaw occurs when the system processes malformed or specially crafted RTT control messages that contain improperly sized or structured XTLV elements. The absence of proper input validation in the unpacking routine means that an attacker can manipulate the length parameters within the XTLV structure to cause memory corruption. This type of vulnerability typically arises from insufficient validation of user-supplied data before memory operations, creating a pathway for malicious actors to overwrite adjacent memory locations with controlled data.
The operational impact of CVE-2023-21078 is severe as it enables local privilege escalation to system-level execution privileges without requiring user interaction for exploitation. This means that an attacker with local access to an Android device could leverage this vulnerability to gain complete system control, potentially leading to full device compromise. The vulnerability affects the Android kernel directly, making it particularly dangerous as it operates at the core level of the operating system. Attackers could use this flaw to install persistent backdoors, extract sensitive data, or disable security mechanisms, effectively rendering the device's security posture compromised. The lack of user interaction requirement makes this vulnerability especially concerning for mobile devices where users may not be aware of the exploitation occurring in the background.
Mitigation strategies for CVE-2023-21078 should focus on immediate patching of affected Android kernel versions, as the vulnerability requires kernel-level modifications to address the buffer overflow condition. Organizations should implement comprehensive monitoring for suspicious RTT protocol activities and network traffic patterns that might indicate exploitation attempts. The recommended approach includes applying security patches from device manufacturers as soon as they become available, which typically involve adding proper bounds checking mechanisms to validate XTLV structure lengths before memory operations. Additionally, system administrators should consider implementing runtime protections such as kernel address space layout randomization and stack canaries to make exploitation more difficult. Security teams should also monitor for potential exploitation attempts through network traffic analysis, particularly focusing on anomalous RTT protocol communications that could indicate malicious activity targeting this specific vulnerability. The ATT&CK framework categorizes this as a privilege escalation technique, specifically targeting kernel-level vulnerabilities to achieve system-level access, making it a critical concern for mobile security posture management.