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CVE Record

CVE-2023-53762: Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync Use-after-free can occur in hci_disconnect_all_sync if a connection is deleted by concurrent processing of a controller event. To prevent this the code now tries to iterate over the list backwards to ensure the links are cleanup before its parents, also it no longer relies on a cursor, instead it always uses the last element since hci_abort_conn_sync is guaranteed to call hci_conn_del. UAF crash log: ================================================================== BUG: KASAN: slab-use-after-free in hci_set_powered_sync (net/bluetooth/hci_sync.c:5424) [bluetooth] Read of size 8 at addr ffff888009d9c000 by task kworker/u9:0/124 CPU: 0 PID: 124 Comm: kworker/u9:0 Tainted: G W 6.5.0-rc1+ #10 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 Workqueue: hci0 hci_cmd_sync_work [bluetooth] Call Trace: <TASK> dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0xdd/0x160 ? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] kasan_report+0xa6/0xe0 ? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] ? __pfx_set_powered_sync+0x10/0x10 [bluetooth] hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] ? __pfx_hci_set_powered_sync+0x10/0x10 [bluetooth] ? __pfx_lock_release+0x10/0x10 ? __pfx_set_powered_sync+0x10/0x10 [bluetooth] hci_cmd_sync_work+0x137/0x220 [bluetooth] process_one_work+0x526/0x9d0 ? __pfx_process_one_work+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? mark_held_locks+0x1a/0x90 worker_thread+0x92/0x630 ? __pfx_worker_thread+0x10/0x10 kthread+0x196/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 </TASK> Allocated by task 1782: kasan_save_stack+0x33/0x60 kasan_set_track+0x25/0x30 __kasan_kmalloc+0x8f/0xa0 hci_conn_add+0xa5/0xa80 [bluetooth] hci_bind_cis+0x881/0x9b0 [bluetooth] iso_connect_cis+0x121/0x520 [bluetooth] iso_sock_connect+0x3f6/0x790 [bluetooth] __sys_connect+0x109/0x130 __x64_sys_connect+0x40/0x50 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Freed by task 695: kasan_save_stack+0x33/0x60 kasan_set_track+0x25/0x30 kasan_save_free_info+0x2b/0x50 __kasan_slab_free+0x10a/0x180 __kmem_cache_free+0x14d/0x2e0 device_release+0x5d/0xf0 kobject_put+0xdf/0x270 hci_disconn_complete_evt+0x274/0x3a0 [bluetooth] hci_event_packet+0x579/0x7e0 [bluetooth] hci_rx_work+0x287/0xaa0 [bluetooth] process_one_work+0x526/0x9d0 worker_thread+0x92/0x630 kthread+0x196/0x1e0 ret_from_fork+0x2c/0x50 ==================================================================

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2023-53762 is a Linux kernel Bluetooth memory-safety bug. A race can leave kernel code using a connection object after it was freed, causing a KASAN-confirmed use-after-free crash. The sources show kernel fixes, but no CVSS score, KEV listing, or active exploitation evidence.

Executive priority

Treat as a targeted kernel-maintenance item, not an emergency based on current evidence. Patch Bluetooth-enabled Linux fleets during normal security cycles, faster for endpoints, appliances, or lab systems where Bluetooth is active.

Technical view

The issue is in Linux Bluetooth hci_sync, specifically hci_disconnect_all_sync. Concurrent controller event handling can delete a connection while disconnect cleanup still references it. The fix changes list traversal and avoids relying on a cursor, using the last element because hci_abort_conn_sync deletes the connection.

Likely exposure

Exposure appears limited to Linux systems running affected kernel builds with Bluetooth enabled or in use. The bundle lists Linux kernel versions including 5.17, 6.4.16, 6.5.3, and 6.6, but the version-range semantics are not fully clear.

Exploitation context

No source in the bundle reports public exploitation, weaponized exploit code, or CISA KEV inclusion. The provided evidence is a kernel crash trace and stable kernel fixes. Impact beyond crash or denial of service is not established in the supplied sources.

Researcher notes

The source evidence points to a concurrency UAF in Bluetooth connection cleanup. The crash path includes hci_set_powered_sync, hci_disconn_complete_evt, and ISO/CIS connection allocation. Version applicability should be confirmed against upstream stable commits or distribution backports.

Mitigation direction

  • Apply vendor kernel updates containing the referenced stable fixes.
  • Prioritize systems where Bluetooth is enabled, exposed, or operationally unnecessary.
  • If patching is delayed, consider disabling Bluetooth where business operations allow.
  • Track Linux distribution advisories for exact fixed package versions.

Validation and detection

  • Inventory Linux hosts and record kernel versions and Bluetooth enablement.
  • Map running kernels against vendor advisories and referenced stable commits.
  • Check whether Bluetooth modules or controllers are active on in-scope systems.
  • Confirm patched hosts are running the updated kernel after reboot.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2023-53762 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux182ee45da083db4e3e621541ccf255bfa9652214, 182ee45da083db4e3e621541ccf255bfa9652214, 182ee45da083db4e3e621541ccf255bfa9652214unaffected
LinuxLinux5.17, 0, 6.4.16, 6.5.3, 6.6affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.