Description

A heap overflow in the a2dp_decoder_sbc.cpp component of Bestechnic Co., Ltd BES2300 Bluetooth Audio SoC firmware v3.x and earlier allows attackers to cause a Denial of Service (DoS) via sending a crafted L2CAP packet.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-09-08T14:17:28.457Z",
  "pubdate": "2026-09-08T14:17:28.457Z",
  "executiveSummary": "This vulnerability involves a heap-based buffer overflow within the a2dp_decoder_sbc.cpp component of the Bestechnic Co., Ltd BES2300 Bluetooth Audio SoC firmware versions v3.x and earlier.\nThe flaw occurs during the processing of L2CAP packets, where improper validation of incoming data lengths leads to memory corruption.\nThe primary impact of this vulnerability is a Denial of Service (DoS), potentially causing the affected device to crash or experience instability when processing malformed Bluetooth packets.\nThe vulnerability resides within the low-level Bluetooth protocol stack handling, which exposes the system to remote exploitation by an attacker in proximity.\nNo authentication or specific user privileges are required to initiate the attack, as it can be triggered by sending a crafted L2CAP packet via the Bluetooth interface.\nSuccessful exploitation compromises the availability of the device, effectively disabling its Bluetooth audio functionality until a manual reset is performed by the user.",
  "technicalDetails": "The root cause of the vulnerability is an insufficient bounds check during the deserialization or copy operation of SBC (Sub-band Coding) data within the a2dp_decoder_sbc.cpp source file.\nThe BES2300 firmware utilizes this component to handle A2DP (Advanced Audio Distribution Profile) streams. When a remote device transmits an L2CAP packet containing a crafted SBC payload, the decoder fails to verify that the incoming data size matches the pre-allocated heap memory buffer.\nThe exploitation process begins when the Bluetooth controller receives an L2CAP packet formatted to trigger the A2DP decoder. Upon reaching the vulnerable function in a2dp_decoder_sbc.cpp, the routine attempts to write the received payload into the heap buffer without confirming that the source data size is within defined boundaries.\nBecause the heap buffer size is static or insufficiently dynamically sized relative to the incoming packet length, the excess data overflows into adjacent memory blocks. This memory corruption overwrites critical heap metadata or adjacent objects, leading to undefined behavior within the firmware's execution environment.\nThe attack flow follows a direct vector: 1) The attacker initiates a connection or utilizes an existing connection to the BES2300 device via Bluetooth. 2) The attacker encapsulates a malformed SBC frame within an L2CAP packet. 3) The target's firmware invokes the decoder function in a2dp_decoder_sbc.cpp to parse the frame. 4) The overflow occurs during the memory copy operation, corrupting the heap and triggering an exception, kernel panic, or system hang.\nAffected versions include all firmware releases of BES2300 up to and including v3.x. The component operates at a low privilege level within the firmware, yet because it resides within the Bluetooth stack, it is accessible over-the-air (OTA). There is no requirement for prior authentication, as the processing of L2CAP packets occurs at the link management layer before higher-level authentication might be enforced.\nThe post-exploitation impact is primarily limited to system instability (Denial of Service). While heap overflows can often be leveraged for arbitrary code execution (ACE), the DoS condition is the guaranteed outcome due to the corruption of essential heap management structures, which typically forces the system watchdog or scheduler to halt operations upon detection of the memory violation."
}