CVE-2024-7139 in RS9116 Bluetooth SDK
Summary
by MITRE • 12/19/2024
Due to an unchecked buffer length, a specially crafted L2CAP packet can cause a buffer overflow. This buffer overflow triggers an assert, which results in a temporary denial of service.
If a watchdog timer is not enabled, a hard reset is required to recover the device.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/29/2025
This vulnerability resides in the Bluetooth Low Energy stack implementation where an unchecked buffer length in the L2CAP (Logical Link Control and Adaptation Protocol) layer creates a condition for buffer overflow exploitation. The flaw occurs when processing specially crafted L2CAP packets that exceed the expected buffer boundaries, allowing malicious actors to manipulate memory layout through crafted packet structures. The vulnerability specifically targets the protocol handling mechanism that does not validate incoming packet lengths against allocated buffer sizes before processing. According to CWE-121, this represents a classic stack-based buffer overflow condition that can be triggered through improper input validation. The attack surface is particularly concerning in embedded systems and IoT devices where Bluetooth connectivity is prevalent and hardware watchdog timers may be disabled or unavailable.
The technical execution of this vulnerability involves crafting L2CAP packets with oversized data payloads that bypass normal validation checks within the Bluetooth stack implementation. When the system attempts to process these malformed packets, the buffer overflow triggers an assertion failure within the protocol handler code. This assertion failure represents a defensive mechanism that terminates the current execution flow but does not gracefully handle the error condition. The system's response to this assertion failure creates a temporary denial of service state where the Bluetooth functionality becomes unavailable until manual intervention occurs. From an ATT&CK perspective, this maps to technique T1499.004 for network denial of service and T1566.001 for spearphishing with social engineering elements in the context of Bluetooth protocol exploitation.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect critical infrastructure and connected devices where Bluetooth is used for communication and control functions. In automotive systems, industrial control equipment, and medical devices, this vulnerability could lead to complete system unavailability requiring physical intervention for recovery. The requirement for a hard reset when watchdog timers are disabled represents a significant operational risk, particularly in environments where device accessibility is limited or where automated recovery mechanisms are not implemented. Devices that rely on continuous Bluetooth connectivity for security functions, data logging, or remote management may experience complete service interruption until manual recovery procedures are executed. The vulnerability's impact is amplified in networked environments where multiple devices could be simultaneously affected, potentially creating cascading failures in connected systems.
Mitigation strategies should focus on implementing proper buffer length validation at the L2CAP packet processing layer, including bounds checking and input validation before memory allocation occurs. System administrators should ensure that watchdog timers are enabled and properly configured to provide automatic recovery mechanisms for affected devices. Firmware updates from vendors should be prioritized to address the root cause through proper memory management and validation procedures. Network segmentation and monitoring should be implemented to detect and alert on suspicious L2CAP packet patterns that could indicate exploitation attempts. Additionally, implementing rate limiting and packet filtering at network boundaries can help prevent exploitation by limiting the ability of attackers to send malformed packets to target systems. The vulnerability highlights the importance of defensive programming practices and proper error handling in embedded systems where resource constraints may lead to inadequate security controls.