CVE-2025-39860
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CVE Details
| Release Date: | 2025-09-19 | |
| Impact: | Moderate | What is this? |
Description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: Fix use-after-free in l2cap_sock_cleanup_listen()
syzbot reported the splat below without a repro.
In the splat, a single thread calling bt_accept_dequeue() freed sk
and touched it after that.
The root cause would be the racy l2cap_sock_cleanup_listen() call
added by the cited commit.
bt_accept_dequeue() is called under lock_sock() except for
l2cap_sock_release().
Two threads could see the same socket during the list iteration
in bt_accept_dequeue():
CPU1 CPU2 (close())
---- ----
sock_hold(sk) sock_hold(sk);
lock_sock(sk) <-- block close()
sock_put(sk)
bt_accept_unlink(sk)
sock_put(sk) <-- refcnt by bt_accept_enqueue()
release_sock(sk)
lock_sock(sk)
sock_put(sk)
bt_accept_unlink(sk)
sock_put(sk) <-- last refcnt
bt_accept_unlink(sk) <-- UAF
Depending on the timing, the other thread could show up in the
"Freed by task" part.
Let's call l2cap_sock_cleanup_listen() under lock_sock() in
l2cap_sock_release().
[0]:
BUG: KASAN: slab-use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
BUG: KASAN: slab-use-after-free in do_raw_spin_lock+0x26f/0x2b0 kernel/locking/spinlock_debug.c:115
Read of size 4 at addr ffff88803b7eb1c4 by task syz.5.3276/16995
CPU: 3 UID: 0 PID: 16995 Comm: syz.5.3276 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
See more information about CVE-2025-39860 from MITRE CVE dictionary and NIST NVD
NOTE: The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 metrics
| Base Score: | 0.0 |
| Vector String: | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N |
| Version: | 3.1 |
| Attack Vector: | Local |
| Attack Complexity: | Low |
| Privileges Required: | Low |
| User Interaction: | None |
| Scope: | Unchanged |
| Confidentiality Impact: | None |
| Integrity Impact: | None |
| Availability Impact: | None |
Errata information
| Platform | Errata | Release Date |
| Oracle Linux version 10 (kernel-uek) | ELSA-2025-25754 | 2025-11-09 |
| Oracle Linux version 7 (kernel-uek) | ELSA-2025-25755 | 2025-11-10 |
| Oracle Linux version 8 (kernel-uek) | ELSA-2025-25755 | 2025-11-10 |
| Oracle Linux version 9 (kernel-uek) | ELSA-2025-25754 | 2025-11-09 |
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