Cloudanix VulnDB

CVE-2026-98737

None

CVSS

—

EPSS

0.2%

Published

Oct 18, 2026

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in how Linux handles Bluetooth device discovery can let nearby attackers crash the system or potentially run code if they can interact with the wireless stack.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Privilege Gain
Component
OS kernel
Class
Use After Free
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Use-after-free in the Linux kernel Bluetooth HCI sync worker when inquiry cache entries are looked up and read without holding hdev->lock, allowing concurrent HCIINQUIRY ioctls to flush and free the entries during hci_acl_create_conn_sync or hci_stop_discovery_sync.

Why it matters to the business

Kernel crashes or potential arbitrary code execution on Linux systems with Bluetooth enabled, disrupting wireless connectivity and device operations until patched.

How an attack unfolds

An attacker with local access issues concurrent Bluetooth discovery and connection commands that race the inquiry cache flush against the sync worker's unprotected reads of freed cache entries.

How to fix it

Apply the upstream fix that holds hdev->lock across cache lookups and copies remote addresses before releasing the lock; rebuild and deploy updated kernel images to affected systems.

How to confirm the fix worked

Confirm kernel builds contain the locking changes around hci_inquiry_cache_update, hci_acl_create_conn_sync, and hci_stop_discovery_sync; re-run KASAN-enabled Bluetooth stress tests to verify absence of slab-use-after-free reports.

Typical attack path

  1. Trigger HCI inquiry via ioctl to populate cache
  2. Initiate concurrent discovery stop or ACL connection from sync worker
  3. Flush cache from another ioctl while worker holds references
  4. Worker dereferences freed slab object leading to KASAN-detected UAF

How to detect it

Inspect kernel logs and dmesg for KASAN slab-use-after-free reports referencing hci_acl_create_conn_sync or hci_stop_discovery_sync called from hci_cmd_sync_work; correlate with Bluetooth ioctl activity.

What your security team should do

  • Prioritize kernel updates for Bluetooth-enabled endpoints within standard patching windows given low EPSS and no KEV listing
  • Disable Bluetooth where not required to reduce attack surface
  • Monitor kernel logs for hci_cmd_sync_work and KASAN UAF signatures in hci_acl_create_conn_sync

The record

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: Fix inquiry cache use-after-free The sync command worker holds hdev->req_lock, but inquiry-cache updates and flushes use hdev->lock. Both hci_acl_create_conn_sync() and hci_stop_discovery_sync() look up entries and read their fields without taking hdev->lock. After either lookup returns, a concurrent HCIINQUIRY ioctl can acquire hdev->lock and flush the cache, freeing the entry. The worker then reads the freed entry while preparing a create-connection or remote-name-cancel command. The list traversal also races with cache updates and removal. KASAN reported these accesses: BUG: KASAN: slab-use-after-free in hci_acl_create_conn_sync+0x5f1/0x650 Workqueue: hci0 hci_cmd_sync_work Call Trace: hci_acl_create_conn_sync+0x5f1/0x650 hci_cmd_sync_work+0x13c/0x290 Allocated by task 90: hci_inquiry_cache_update+0x3e6/0x7d0 hci_inquiry_result_evt+0x3cb/0x560 Freed by task 93: hci_inquiry_cache_flush+0x111/0x2b0 hci_inquiry+0x2f2/0x780 hci_sock_ioctl+0x269/0x5f0 BUG: KASAN: slab-use-after-free in hci_stop_discovery_sync+0x3b1/0x3c0 Workqueue: hci0 hci_cmd_sync_work Call Trace: hci_stop_discovery_sync+0x3b1/0x3c0 hci_cmd_sync_work+0x173/0x300 Allocated by task 86: hci_inquiry_cache_update+0x483/0x940 hci_inquiry_result_evt+0x3cb/0x560 Freed by task 91: hci_inquiry_cache_flush+0x13e/0x2f0 hci_inquiry+0x2f2/0x780 hci_sock_ioctl+0x269/0x5f0 Hold hdev->lock across each lookup and all reads from its result. Copy the remote address before unlocking so discovery cancellation does not retain a cache entry pointer. Release the lock before sending synchronous HCI commands, since their completion handlers may need the same lock.

Affected packages

Ecosystem Package Introduced Fixed