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CVE Record

CVE-2026-23167: nfc: nci: Fix race between rfkill and nci_unregister_device().

In the Linux kernel, the following vulnerability has been resolved: nfc: nci: Fix race between rfkill and nci_unregister_device(). syzbot reported the splat below [0] without a repro. It indicates that struct nci_dev.cmd_wq had been destroyed before nci_close_device() was called via rfkill. nci_dev.cmd_wq is only destroyed in nci_unregister_device(), which (I think) was called from virtual_ncidev_close() when syzbot close()d an fd of virtual_ncidev. The problem is that nci_unregister_device() destroys nci_dev.cmd_wq first and then calls nfc_unregister_device(), which removes the device from rfkill by rfkill_unregister(). So, the device is still visible via rfkill even after nci_dev.cmd_wq is destroyed. Let's unregister the device from rfkill first in nci_unregister_device(). Note that we cannot call nfc_unregister_device() before nci_close_device() because 1) nfc_unregister_device() calls device_del() which frees all memory allocated by devm_kzalloc() and linked to ndev->conn_info_list 2) nci_rx_work() could try to queue nci_conn_info to ndev->conn_info_list which could be leaked Thus, nfc_unregister_device() is split into two functions so we can remove rfkill interfaces only before nci_close_device(). [0]: DEBUG_LOCKS_WARN_ON(1) WARNING: kernel/locking/lockdep.c:238 at hlock_class kernel/locking/lockdep.c:238 [inline], CPU#0: syz.0.8675/6349 WARNING: kernel/locking/lockdep.c:238 at check_wait_context kernel/locking/lockdep.c:4854 [inline], CPU#0: syz.0.8675/6349 WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x39d/0x2cf0 kernel/locking/lockdep.c:5187, CPU#0: syz.0.8675/6349 Modules linked in: CPU: 0 UID: 0 PID: 6349 Comm: syz.0.8675 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026 RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4854 [inline] RIP: 0010:__lock_acquire+0x3a4/0x2cf0 kernel/locking/lockdep.c:5187 Code: 18 00 4c 8b 74 24 08 75 27 90 e8 17 f2 fc 02 85 c0 74 1c 83 3d 50 e0 4e 0e 00 75 13 48 8d 3d 43 f7 51 0e 48 c7 c6 8b 3a de 8d <67> 48 0f b9 3a 90 31 c0 0f b6 98 c4 00 00 00 41 8b 45 20 25 ff 1f RSP: 0018:ffffc9000c767680 EFLAGS: 00010046 RAX: 0000000000000001 RBX: 0000000000040000 RCX: 0000000000080000 RDX: ffffc90013080000 RSI: ffffffff8dde3a8b RDI: ffffffff8ff24ca0 RBP: 0000000000000003 R08: ffffffff8fef35a3 R09: 1ffffffff1fde6b4 R10: dffffc0000000000 R11: fffffbfff1fde6b5 R12: 00000000000012a2 R13: ffff888030338ba8 R14: ffff888030338000 R15: ffff888030338b30 FS: 00007fa5995f66c0(0000) GS:ffff8881256f8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7e72f842d0 CR3: 00000000485a0000 CR4: 00000000003526f0 Call Trace: <TASK> lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:3940 __flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:3982 nci_close_device+0x302/0x630 net/nfc/nci/core.c:567 nci_dev_down+0x3b/0x50 net/nfc/nci/core.c:639 nfc_dev_down+0x152/0x290 net/nfc/core.c:161 nfc_rfkill_set_block+0x2d/0x100 net/nfc/core.c:179 rfkill_set_block+0x1d2/0x440 net/rfkill/core.c:346 rfkill_fop_write+0x461/0x5a0 net/rfkill/core.c:1301 vfs_write+0x29a/0xb90 fs/read_write.c:684 ksys_write+0x150/0x270 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa59b39acb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fa5995f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fa59b615fa0 RCX: 00007fa59b39acb9 RDX: 0000000000000008 RSI: 0000200000000080 RDI: 0000000000000007 RBP: 00007fa59b408bf7 R08: ---truncated---

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2026-23167 is a Linux kernel race condition in NFC NCI cleanup and rfkill handling. A device could remain reachable through rfkill after an internal workqueue was destroyed, leading to unsafe kernel behavior. The source shows a syzbot report and upstream stable fixes, but does not provide CVSS, confirmed exploitation, or business-impact detail.

Executive priority

Treat this as a kernel hygiene issue with uncertain severity, not a confirmed emergency. Patch through normal kernel maintenance unless NFC is broadly enabled on sensitive systems, where expedited validation is reasonable. The main risk is kernel instability or undefined behavior from a race condition, with no confirmed exploitation in the supplied evidence.

Technical view

The race occurs when nci_unregister_device() destroys nci_dev.cmd_wq before nfc_unregister_device() removes rfkill visibility. rfkill can then call nci_close_device(), which flushes a destroyed workqueue. The fix splits NFC unregister handling so rfkill interfaces are removed before nci_close_device(), while preserving later cleanup ordering for connection list safety.

Likely exposure

Exposure appears limited to Linux systems with affected NFC NCI/rfkill code paths enabled or reachable. The bundle lists Linux kernel affected entries including 5.10.249, 5.15.199, 6.1.162, 6.6.123, 6.12.69, 6.18.9, and 6.19, but exact deployed package status depends on vendor backports.

Exploitation context

No active exploitation is cited, and KEV is false. The report came from syzbot without a reproducer. Evidence points to local kernel interface interaction involving NFC virtual device cleanup and rfkill writes, not a remote network attack path. Practical exploitability is not established by the supplied sources.

Researcher notes

The key evidence is the upstream kernel fix rationale, not an exploit report. The source describes ordering constraints: rfkill removal must occur before nci_close_device(), while full nfc_unregister_device() cannot move earlier because devm-managed connection-list memory and nci_rx_work() cleanup could be mishandled.

Mitigation direction

  • Track your Linux vendor advisory for CVE-2026-23167 and NFC-related kernel updates.
  • Apply kernel updates containing the referenced stable commits when available for your distribution.
  • Prioritize systems with NFC hardware, NFC modules, or virtual NFC testing interfaces enabled.
  • Consider disabling unused NFC functionality where operationally acceptable until patched.

Validation and detection

  • Inventory kernel versions and vendor package builds across Linux fleets.
  • Check whether NFC NCI and rfkill interfaces are enabled or loaded on affected systems.
  • Confirm vendor kernels include one of the referenced upstream stable fixes or equivalent backport.
  • Review kernel logs for NFC, rfkill, lockdep, or workqueue warnings if NFC is used.
Prepared
Confidence
medium
Sources
9

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

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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
0ADP providers
8Source links

Vulnerability timeline

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  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

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux6a2968aaf50c7a22fced77a5e24aa636281efca8, 6a2968aaf50c7a22fced77a5e24aa636281efca8, 6a2968aaf50c7a22fced77a5e24aa636281efca8, 6a2968aaf50c7a22fced77a5e24aa636281efca8, 6a2968aaf50c7a22fced77a5e24aa636281efca8, 6a2968aaf50c7a22fced77a5e24aa636281efca8, 6a2968aaf50c7a22fced77a5e24aa636281efca8unaffected
LinuxLinux3.2, 0, 5.10.249, 5.15.199, 6.1.162, 6.6.123, 6.12.69, 6.18.9, 6.19affected
Weakness

CWE details

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