Linux Kernel L2CAP UAF via Unprotected Bluetooth Registration
CVE-2026-23461 Published on April 3, 2026
Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user
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.
Products Associated with CVE-2026-23461
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Affected Versions
Linux:- Version efc30877bd4bc85fefe98d80af60fafc86e5775e and below 11a87dd5df428a4b79a84d2790cac7f3c73f1f0d is affected.
- Version f87271d21dd4ee83857ca11b94e7b4952749bbae and below c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf is affected.
- Version ab4eedb790cae44313759b50fe47da285e2519d5 and below da3000cbe4851458a22be38bb18c0689c39fdd5f is affected.
- Version ab4eedb790cae44313759b50fe47da285e2519d5 and below 71030f3b3015a412133a805ff47970cdcf30c2b8 is affected.
- Version ab4eedb790cae44313759b50fe47da285e2519d5 and below 752a6c9596dd25efd6978a73ff21f3b592668f4a is affected.
- Version 18ab6b6078fa8191ca30a3065d57bf35d5635761 is affected.
- Version 6.14 is affected.
- Before 6.14 is unaffected.
- Version 6.6.130, <= 6.6.* is unaffected.
- Version 6.12.78, <= 6.12.* is unaffected.
- Version 6.18.20, <= 6.18.* is unaffected.
- Version 6.19.10, <= 6.19.* is unaffected.
- Version 7.0-rc5, <= * is unaffected.