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Vulnerability record · CVE-2026-23461 · published 3 April 2026

CVE-2026-23461: Linux kernel use after free vulnerability

Linux · Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to conn->users. However, l2cap_register_user() and l2cap_unregister_user() don't use conn->lock, creating a race condition where these functions can access conn->users and conn->hchan concurrently with l2cap_conn_del(). This can lead to use-after-free and list corruption bugs, as reported by syzbot. Fix this by changing l2cap_register_user() and l2cap_unregister_user() to use conn->lock instead of hci_dev_lock(), ensuring consistent locking for the l2cap_conn structure.

8.8 CVSS 3.1 High EPSS 0.25% · top 85.6% CWE-416 · Use after free
8.8CVSS 3.1 base score
0.25%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References
24 Jul 2026Last modified by NVD

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to conn->users. However, l2cap_register_user() and l2cap_unregister_user() don't use conn->lock, creating a race condition where these functions can access conn->users and conn->hchan concurrently with l2cap_conn_del(). This can lead to use-after-free and list corruption bugs, as reported by syzbot. Fix this by changing l2cap_register_user() and l2cap_unregister_user() to use conn->lock instead of hci_dev_lock(), ensuring consistent locking for the l2cap_conn structure.

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/11a87dd5df428a4b79a84d2790cac7f3c73f1f0d Patch
https://git.kernel.org/stable/c/71030f3b3015a412133a805ff47970cdcf30c2b8 Patch
https://git.kernel.org/stable/c/752a6c9596dd25efd6978a73ff21f3b592668f4a Patch
https://git.kernel.org/stable/c/c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf Patch
https://git.kernel.org/stable/c/da3000cbe4851458a22be38bb18c0689c39fdd5f Patch

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Source: NIST National Vulnerability Database (record CVE-2026-23461), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.