CVE-2026-23461: Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-03 · updated 2026-10-19
Weakness: CWE-416

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.

Affected products

Linux kernel: from 6.6.84 before 6.6.130; from 6.12.20 before 6.12.78; from 6.13.8 before 6.14; from 6.14.1 before 6.18.20; from 6.19 before 6.19.10; 6.14, 6.14-rc3, 6.14-rc4, 6.14-rc5, 6.14-rc6, 6.14-rc7 (+4) — fixed in 6.12.78, 6.14, 6.18.20, 6.19.10, 6.6.130

How to fix

Upgrade to a fixed version: Linux kernel 6.12.78, 6.14, 6.18.20, 6.19.10. Check the vendor advisory for mitigations.

References

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