CVE-2026-53071: Linux Kernel Bluetooth Race Condition

CVE-2026-53071 Overview

CVE-2026-53071 is a race condition in the Linux kernel Bluetooth subsystem. The flaw resides in the L2CAP (Logical Link Control and Adaptation Protocol) handler l2cap_ecred_reconf_rsp(), which invokes l2cap_chan_del() without first acquiring l2cap_chan_lock(). A remote Bluetooth Low Energy (BLE) device within radio range can send a crafted Enhanced Credit Based Flow Control (ECRED) reconfiguration response to corrupt the channel list while another kernel thread iterates it. The upstream fix adds l2cap_chan_hold() and l2cap_chan_lock() around the l2cap_chan_del() call, mirroring the locking pattern already used by l2cap_ecred_conn_rsp() and l2cap_conn_del().

Critical Impact
A remote unauthenticated BLE peer in radio range can trigger kernel memory corruption through a channel list race, leading to denial of service and potential privilege escalation.

Affected Products

Linux kernel Bluetooth subsystem (net/bluetooth/l2cap_core.c)
Linux distributions shipping affected stable kernels prior to the referenced fix commits
Systems with Bluetooth Low Energy enabled and reachable to attackers

Discovery Timeline

2026-06-24 - CVE-2026-53071 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-53071

Vulnerability Analysis

The Linux Bluetooth stack uses per-channel mutexes to serialize access to L2CAP channel state. Most code paths that delete a channel acquire l2cap_chan_lock() before calling l2cap_chan_del(), which unlinks the channel from connection lists and tears down its state. The handler l2cap_ecred_reconf_rsp() processes ECRED reconfiguration responses from a peer but omits this lock acquisition. When the handler removes a channel while another thread iterates the channel list, the list can be corrupted mid-traversal. This is a classic race condition leading to memory safety violations in kernel context. Exploitation requires only BLE radio proximity, not authenticated pairing in all configurations, so the attack surface extends to any nearby attacker with a programmable Bluetooth radio.

Root Cause

The root cause is missing mutex acquisition in l2cap_ecred_reconf_rsp(). The function manipulates channel objects and calls l2cap_chan_del() without holding the channel lock, breaking the locking invariant assumed by concurrent readers and writers of the channel list.

Attack Vector

A remote BLE device sends a crafted ECRED reconfiguration response frame to a vulnerable host. The response is parsed by l2cap_ecred_reconf_rsp(), which races against other kernel threads accessing the same channel list. The result is list corruption, use-after-free, or other memory safety errors in kernel space.

No public proof-of-concept exploit code is available. See the upstream kernel commits referenced below for the precise change set.

Detection Methods for CVE-2026-53071

Indicators of Compromise

Unexpected kernel oops or panic messages referencing l2cap_chan_del, l2cap_ecred_reconf_rsp, or l2cap_core.c in dmesg or journalctl -k
KASAN or list debugging warnings tied to Bluetooth L2CAP channel structures
Unexplained Bluetooth service crashes (bluetoothd) or HCI interface resets following nearby BLE traffic

Detection Strategies

Inventory running kernel versions across the fleet and compare against the fixed stable branches listed in the kernel.org commit references
Enable kernel list debugging (CONFIG_DEBUG_LIST) and KASAN on test systems to surface race-induced corruption
Capture Bluetooth HCI traffic on at-risk hosts and review for malformed L2CAP ECRED reconfiguration response frames

Monitoring Recommendations

Forward kernel logs to a centralized log platform and alert on Bluetooth-related oops, BUG, or KASAN traces
Monitor for systems advertising Bluetooth services that do not require Bluetooth for business function
Track patch compliance on Linux endpoints, servers, and embedded devices that ship with BLE radios

How to Mitigate CVE-2026-53071

Immediate Actions Required

Apply the latest stable kernel update from your Linux distribution that incorporates the upstream fix commits
Disable the Bluetooth subsystem on systems that do not require it by unloading the bluetooth and btusb modules and blacklisting them
Restrict physical and radio-frequency access to systems running unpatched kernels until updates are deployed

Patch Information

The fix adds l2cap_chan_hold() and l2cap_chan_lock() before l2cap_chan_del() and releases them with l2cap_chan_unlock() and l2cap_chan_put() afterward in l2cap_ecred_reconf_rsp(). Upstream commits: Kernel Commit 0ccd75c, Kernel Commit 330b20e, Kernel Commit 4277649, Kernel Commit 5501d05, Kernel Commit 77a853a, Kernel Commit 96dca51, Kernel Commit dc89961, and Kernel Commit fe1188ab.

Workarounds

Disable Bluetooth on hosts that do not require it: systemctl disable --now bluetooth.service and unload bluetooth related kernel modules
Blacklist Bluetooth modules to prevent reload at boot using a file in /etc/modprobe.d/
For mobile or laptop fleets that require Bluetooth, restrict BLE advertising and pairing to known peripherals through device policy

bash

# Configuration example: disable Bluetooth stack on Linux hosts that do not need it
sudo systemctl disable --now bluetooth.service
echo 'install bluetooth /bin/true' | sudo tee /etc/modprobe.d/disable-bluetooth.conf
echo 'install btusb /bin/true'    | sudo tee -a /etc/modprobe.d/disable-bluetooth.conf
sudo rmmod btusb bluetooth 2>/dev/null

# Verify the running kernel after patching
uname -r