CVE-2026-79376: BES2300 Bluetooth SoC DoS Vulnerability

CVE-2026-79376 Overview

CVE-2026-79376 is a denial-of-service vulnerability in the l2cap_handle_data() function of the Bestechnic Co., Ltd BES2300 Bluetooth Audio System-on-Chip (SoC) firmware. Versions v3.x and earlier improperly validate incoming Logical Link Control and Adaptation Protocol (L2CAP) packets. An attacker within Bluetooth range can send a crafted L2CAP packet to crash the target device without authentication or user interaction. The BES2300 SoC is used in wireless audio products such as true wireless stereo (TWS) earbuds and Bluetooth speakers. The weakness is classified as improper input validation [CWE-20].

Critical Impact
An unauthenticated attacker within Bluetooth radio range can trigger a device crash by sending a single malformed L2CAP frame, disrupting audio service on affected BES2300-based products.

Affected Products

Bestechnic BES2300 Bluetooth Audio SoC firmware v3.x
Bestechnic BES2300 Bluetooth Audio SoC firmware versions earlier than v3.x
Downstream audio products (TWS earbuds, headsets, speakers) built on the BES2300 platform

Discovery Timeline

2026-09-08 - CVE-2026-79376 published to the National Vulnerability Database (NVD)
2026-09-09 - Last updated in NVD database

Technical Details for CVE-2026-79376

Vulnerability Analysis

The flaw resides in l2cap_handle_data(), the routine responsible for parsing inbound L2CAP payloads within the BES2300 Bluetooth stack. L2CAP sits directly above the Host Controller Interface (HCI) and multiplexes higher-layer Bluetooth protocols, so any deserialization defect at this layer is reachable before authentication completes. Sending a crafted L2CAP packet causes the firmware to enter an unrecoverable state, resulting in a denial of service on the SoC. Because the BES2300 typically drives an entire audio product, a crash removes audio playback, call functionality, and pairing until the device is manually reset.

Root Cause

The root cause is improper input validation [CWE-20] within l2cap_handle_data(). The parser does not adequately verify length fields, channel identifiers, or fragmentation state before acting on attacker-controlled bytes. Refer to the Bestechnic CVE-2026-79376 Documentation for vendor-supplied technical detail.

Attack Vector

Exploitation requires adjacent-network access over Bluetooth radio. No privileges or user interaction are required. The attacker pairs the radio channel with the target, then transmits a malformed L2CAP frame carrying values that violate protocol assumptions. The firmware processes the frame in l2cap_handle_data() and halts, denying service to legitimate connections.

No public proof-of-concept exploit is currently listed for this CVE. See the BES2300 Resource Overview and Bestechnic Homepage for vendor references.

Detection Methods for CVE-2026-79376

Indicators of Compromise

Unexpected reboots, audio dropouts, or Bluetooth link resets on BES2300-based devices in the presence of nearby unknown Bluetooth transmitters.
Repeated L2CAP connection attempts from unrecognized Bluetooth Device Addresses (BD_ADDR) captured by nearby wireless monitoring equipment.
Bluetooth capture files showing malformed L2CAP frames with invalid length or channel ID (CID) fields directed at affected devices.

Detection Strategies

Passively capture 2.4 GHz Bluetooth traffic in high-value environments using tools such as Ubertooth or a Bluetooth sniffer, and inspect L2CAP headers for length and CID anomalies.
Correlate device crash telemetry from mobile device management (MDM) or fleet audio-management platforms with timestamps of anomalous Bluetooth activity.
Alert on repeated failed L2CAP connection attempts followed by device unavailability, which is a signature of DoS probing.

Monitoring Recommendations

Track firmware versions across BES2300-based inventory and flag any device still reporting a v3.x or earlier build.
Log Bluetooth pairing and disconnect events from managed endpoints and forward them to a centralized SIEM for correlation.
Monitor physical areas hosting sensitive conversations for rogue Bluetooth transmitters that could be staging adjacent-radio attacks.

How to Mitigate CVE-2026-79376

Immediate Actions Required

Inventory all products that embed the Bestechnic BES2300 SoC and identify firmware versions currently deployed.
Restrict use of affected devices in sensitive environments where a denial of Bluetooth audio would disrupt operations, such as executive briefings or medical settings.
Disable Bluetooth on affected devices when not required, reducing the exposure window for adjacent-radio attacks.

Patch Information

Consult the Bestechnic CVE-2026-79376 Documentation and the Bestechnic Homepage for vendor firmware updates. Downstream vendors that ship BES2300-based products must republish updated firmware through their own update channels. Apply the vendor-supplied firmware update to any device running firmware v3.x or earlier as soon as it becomes available.

Workarounds

Keep affected devices in non-discoverable mode and unpair unknown Bluetooth Device Addresses.
Operate affected devices only in environments free of unknown Bluetooth transmitters until firmware is updated.
Retire or replace BES2300-based products in high-assurance deployments if the vendor cannot supply a timely firmware fix.

bash

# Example: audit paired Bluetooth devices on a Linux management host
bluetoothctl paired-devices
bluetoothctl remove <BD_ADDR>   # remove unknown or untrusted peers