CVE-2026-97975

CVE CVE-2026-97975EUVD EUVD-2026-86629Published 2026-09-25T10:23:13.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sysfs: Fix NULL pointer dereference in device_del() A NULL pointer dereference in klist_put() occurs when a child device (such as a BNEP network device in bnep_session) is concurrently being unregistered while hci_conn_del_sysfs() reparents child devices. This is caused by a race condition between hci_conn_del_sysfs() and concurrent child device unregistration (e.g. bnep_session calling unregister_netdev()). During device unregistration, device_del() snapshots a non-NULL parent pointer. Concurrently, hci_conn_del_sysfs() finds the child device using device_find_any_child() and calls device_move() to reparent it to NULL, which removes the node from its parent's klist and clears knode_parent. Subsequently, device_del() calls klist_del(&dev->p->knode_parent) using the stale parent snapshot, causing klist_put() to dereference knode_klist(n)->put on an already removed node, resulting in a NULL pointer dereference. This race was introduced by commit 27aabf27fd01 ("Bluetooth: fix use-after-free in device_for_each_child()"), which replaced device_find_child(..., __match_tty) with device_find_any_child() in hci_conn_del_sysfs(). That change was intended to avoid a use-after-free where conn->dev outlived its parent hdev->dev when child devices held references to conn->dev, because conn->dev only held a reference to hdev->dev while registered in sysfs. Fix the issue properly by taking an explicit reference to the parent device with get_device(&hdev->dev) in hci_conn_init_sysfs() and dropping it with put_device(parent) in bt_link_release() when the conn device is freed. This ensures that hdev->dev remains valid for the entire lifecycle of conn->dev, resolving the underlying use-after-free. With the parent reference held properly, restore the __match_tty filter in hci_conn_del_sysfs() so that device_move() is only invoked on persistent RFCOMM TTY devices as originally intended, eliminating the race condition with unregistering network devices.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux 6.13; 27aabf27fd014ae037cc179c61b0bee7cff55b3d <eeabdb25c3209569367e99a85ca9a503b64a646d; patch: 6.18.53; 27aabf27fd014ae037cc179c61b0bee7cff55b3d <9e9ece97b8e716890793de261574b8efef7d8702; patch: 7.2.7; patch: 0; 6.1.120 <6.2; 6.6.64 <6.7; a9584c897d1cba6265c78010bbb45ca5722c88bc; patch: 7.3-rc3; fb91ce37dc9a37ea23cf32b6d7b667004e93d4c5; 5.10.231 <5.11; 6894717a1ea363c5a27010ba604f957c309d282d; 6.11.11 <6.12; 91e2a2e4d1336333804cd31162984f01ad8cc70f; 0f67ca2a80acf8b207240405b7f72d660665d3df; 7b277bd569bb6a2777f0014f84b4344f444fd49d; 5.4.297 <5.5; 5.15.174 <5.16; de5a44f351ca7efd9add9851b218f5353e2224b7; 6.12.2 <6.13; 27aabf27fd014ae037cc179c61b0bee7cff55b3d <9b851b09b392da68bd715601f10a5adb2d8d19b8

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

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• Linux — Linux

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