CVE-2026-98737
Received Received - Intake

Use-After-Free in Linux Kernel Bluetooth HCI Sync

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98737
EUVD
EUVD-2026-103822

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
Linux Linux cf75ad8b41d2aa06f98f365d42a3ae8b059daddd
Linux Linux cf75ad8b41d2aa06f98f365d42a3ae8b059daddd
Linux Linux cf75ad8b41d2aa06f98f365d42a3ae8b059daddd
Linux Linux cf75ad8b41d2aa06f98f365d42a3ae8b059daddd
Linux Linux 5.17

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Exploitability

CWE
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's Bluetooth subsystem. It occurs when the sync command worker accesses Bluetooth inquiry cache entries without proper locking, allowing a race condition where entries are freed while still in use. This leads to memory corruption and potential system crashes.

Detection Guidance

This vulnerability is specific to the Linux kernel's Bluetooth subsystem and may not have direct detection commands. However, you can check for kernel logs indicating slab-use-after-free errors related to hci_acl_create_conn_sync or hci_stop_discovery_sync using dmesg or journalctl.

Impact Analysis

This vulnerability could cause system instability or crashes when Bluetooth operations are performed. An attacker within Bluetooth range might exploit this to trigger kernel memory corruption, potentially leading to denial of service or privilege escalation on affected systems.

Mitigation Strategies

Update your Linux kernel to the latest stable version that includes the fix for this vulnerability. If immediate patching is not possible, consider disabling Bluetooth functionality temporarily until the update is applied.

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