CVE-2026-28527 Overview
BlueKitchen BTstack versions prior to 1.8.1 contain an out-of-bounds read vulnerability (CWE-125) in the AVRCP Controller GET_PLAYER_APPLICATION_SETTING_ATTRIBUTE_TEXT and GET_PLAYER_APPLICATION_SETTING_VALUE_TEXT handlers. This vulnerability allows nearby attackers within Bluetooth range to read beyond packet boundaries, potentially leading to information disclosure and device crashes.
The vulnerability exists in the VENDOR_DEPENDENT response handling logic of the Audio/Video Remote Control Profile (AVRCP) implementation. An attacker who can establish a paired Bluetooth Classic connection can send specially crafted VENDOR_DEPENDENT responses to trigger out-of-bounds memory reads on affected devices.
Critical Impact
Nearby attackers with Bluetooth pairing capability can exploit this vulnerability to cause information disclosure and potential denial of service through device crashes on IoT and embedded systems running vulnerable BTstack versions.
Affected Products
- BlueKitchen BTstack versions prior to 1.8.1
- IoT devices and embedded systems utilizing vulnerable BTstack Bluetooth implementations
- Devices implementing AVRCP Controller functionality with BTstack
Discovery Timeline
- 2026-03-30 - CVE-2026-28527 published to NVD
- 2026-04-01 - Last updated in NVD database
Technical Details for CVE-2026-28527
Vulnerability Analysis
This out-of-bounds read vulnerability affects the AVRCP Controller component of BTstack, specifically within the handlers for GET_PLAYER_APPLICATION_SETTING_ATTRIBUTE_TEXT and GET_PLAYER_APPLICATION_SETTING_VALUE_TEXT commands. The vulnerability is classified under CWE-125 (Out-of-bounds Read), indicating improper boundary validation when processing incoming Bluetooth packets.
The AVRCP protocol is used for controlling audio/video equipment via Bluetooth, allowing devices to send commands for playback control, volume adjustment, and metadata retrieval. The vulnerable handlers process VENDOR_DEPENDENT responses that contain player application setting information. When malformed responses are received, the code fails to properly validate packet boundaries before reading data, allowing access to memory outside the intended buffer region.
The adjacent network attack vector requires the attacker to be within Bluetooth range of the target device. While user interaction is required (Bluetooth pairing must be established), this represents a realistic attack scenario for IoT devices, embedded systems, automotive infotainment systems, and other Bluetooth-enabled equipment running BTstack.
Root Cause
The root cause of CVE-2026-28527 is insufficient bounds checking in the AVRCP Controller response parsing code. When processing GET_PLAYER_APPLICATION_SETTING_ATTRIBUTE_TEXT and GET_PLAYER_APPLICATION_SETTING_VALUE_TEXT VENDOR_DEPENDENT responses, the handler does not properly validate that the data length fields within the packet correspond to the actual packet size. This allows a malicious peer to craft packets with length values that exceed the actual data present, causing the parser to read beyond the allocated packet buffer.
Attack Vector
The attack requires adjacent network access via Bluetooth Classic connectivity. An attacker must:
- Be within Bluetooth range of the target device (typically 10-100 meters depending on device class)
- Establish a paired Bluetooth Classic connection with the vulnerable device
- Initiate an AVRCP session where the vulnerable device acts as the AVRCP Controller
- Send specially crafted VENDOR_DEPENDENT responses with malformed length fields to the GET_PLAYER_APPLICATION_SETTING_ATTRIBUTE_TEXT or GET_PLAYER_APPLICATION_SETTING_VALUE_TEXT requests
The vulnerability is triggered when the AVRCP Controller processes these malformed responses, causing out-of-bounds memory reads that may leak sensitive information from adjacent memory regions or cause the application to crash.
The out-of-bounds read occurs in the AVRCP Controller handlers when processing VENDOR_DEPENDENT responses. The vulnerable code path fails to validate packet boundaries against the specified data lengths, allowing memory reads beyond the packet buffer. For detailed technical analysis, see the VulnCheck Advisory for BTstack.
Detection Methods for CVE-2026-28527
Indicators of Compromise
- Unexpected Bluetooth connection attempts from unknown or suspicious devices
- Application crashes or abnormal termination of Bluetooth services on embedded devices
- Memory access violations or segmentation faults in BTstack-based applications
- Unusual AVRCP VENDOR_DEPENDENT response patterns in Bluetooth traffic logs
Detection Strategies
- Monitor Bluetooth traffic for malformed AVRCP VENDOR_DEPENDENT responses with inconsistent length fields
- Implement application-level crash monitoring for BTstack-based services to detect exploitation attempts
- Deploy memory safety monitoring tools on devices where feasible to detect out-of-bounds read operations
- Review Bluetooth pairing logs for unauthorized or suspicious device connections
Monitoring Recommendations
- Enable Bluetooth HCI logging on development and test devices to capture protocol-level traffic for analysis
- Implement alerting for Bluetooth service crashes or unexpected restarts on production devices
- Monitor for multiple failed Bluetooth connection attempts that may indicate reconnaissance activity
- Consider implementing network segmentation to limit Bluetooth exposure in sensitive environments
How to Mitigate CVE-2026-28527
Immediate Actions Required
- Upgrade BTstack to version 1.8.1 or later, which contains the fix for this vulnerability
- Review deployed devices for vulnerable BTstack versions and prioritize firmware updates
- Disable Bluetooth functionality on affected devices where possible until patches can be applied
- Limit Bluetooth pairing to trusted devices only and review existing paired device lists
Patch Information
BlueKitchen has released BTstack version 1.8.1 which addresses this out-of-bounds read vulnerability. The fix implements proper boundary validation in the AVRCP Controller handlers to ensure packet data is not read beyond allocated buffer limits.
Organizations using BTstack should upgrade to version 1.8.1 or later. The patch is available from the GitHub BTstack Release 1.8.1.
For additional technical details about this vulnerability, refer to the VulnCheck Advisory for BTstack.
Workarounds
- Disable AVRCP Controller functionality if not required for device operation
- Implement Bluetooth connection filtering to restrict pairing to known, trusted devices only
- Reduce Bluetooth transmit power to limit the physical range of potential attacks
- Deploy physical security controls in environments where Bluetooth-enabled devices operate
# Example: Verify BTstack version in your build system
grep -r "BTSTACK_VERSION" /path/to/btstack/include/
# Ensure version is 1.8.1 or later before deployment
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
