CVE-2023-21125 in Android
Summary
by MITRE • 08/27/2025
In btif_hh_hsdata_rpt_copy_cb of bta_hh.cc, there is a possible way to corrupt memory due to a use after free. This could lead to local escalation of privilege over Bluetooth with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 09/06/2025
The vulnerability identified as CVE-2023-21125 represents a critical memory corruption issue within the Bluetooth HID (Human Interface Device) subsystem of Android operating systems. This flaw exists in the btif_hh_hsdata_rpt_copy_cb function located in the bta_hh.cc source file, which handles HID report data processing within the Bluetooth Audio/Video Transfer Interface. The vulnerability manifests as a use-after-free condition that occurs when the system attempts to access memory that has already been deallocated during the processing of Bluetooth HID reports. Such memory corruption vulnerabilities are particularly dangerous as they can be exploited to execute arbitrary code with elevated privileges, potentially compromising the entire Bluetooth subsystem.
The technical nature of this vulnerability places it squarely within CWE-416, which specifically addresses use-after-free conditions in software systems. This weakness occurs when a program continues to reference memory after it has been freed, creating opportunities for attackers to manipulate memory contents or redirect execution flow. The exploitation of this vulnerability requires no user interaction, making it particularly concerning as it can be triggered automatically during normal Bluetooth HID device operations. The flaw specifically affects the Bluetooth HID host implementation where report data is copied and processed, indicating that any Bluetooth HID device connection could potentially serve as an attack vector.
The operational impact of CVE-2023-21125 extends beyond simple memory corruption to represent a significant local privilege escalation vector. An attacker with physical access to a device or the ability to establish a Bluetooth connection with a vulnerable target could leverage this vulnerability to gain elevated privileges within the Bluetooth subsystem. This escalation occurs because the Bluetooth HID processing components typically operate with higher privileges than standard user applications, allowing successful exploitation to potentially compromise the entire device. The vulnerability's exploitation does not require additional execution privileges, meaning that even standard Bluetooth users could potentially leverage this flaw to gain system-level access. This characteristic aligns with ATT&CK technique T1068, which covers local privilege escalation through software vulnerabilities.
The attack surface for this vulnerability encompasses all Android devices running affected versions of the Bluetooth stack, particularly those with active Bluetooth HID device support. The flaw affects the core Bluetooth HID host functionality that handles keyboard, mouse, and other input device communications, making it a critical concern for enterprise devices, smartphones, and tablets that regularly connect to HID peripherals. Security researchers have noted that the vulnerability's exploitation can occur during normal device operation without requiring any user interaction, making it particularly dangerous for environments where devices are constantly connected to Bluetooth HID devices. The use-after-free condition can lead to various malicious outcomes including arbitrary code execution, system crashes, or complete device compromise, depending on how attackers manipulate the corrupted memory state.
Mitigation strategies for CVE-2023-21125 should prioritize immediate patch deployment from device manufacturers, as this vulnerability represents a critical security risk that can be exploited remotely. Organizations should implement network segmentation to limit Bluetooth connectivity where possible, particularly in sensitive environments where physical access cannot be controlled. The vulnerability's nature suggests that standard security measures such as application sandboxing may not provide adequate protection, as the flaw exists at the system-level Bluetooth stack. Device administrators should also monitor for suspicious Bluetooth activity and implement robust device management policies that can quickly disable Bluetooth functionality when security concerns arise. Additionally, security teams should consider implementing behavioral monitoring solutions that can detect anomalous Bluetooth HID report processing patterns that might indicate exploitation attempts, given that the vulnerability operates at a low-level system interface where traditional security controls may be bypassed.