High 7.5Published Oct 30, 2025

CVE-2025-40090ksmbd: fix recursive locking in RPC handle list access

Updated under an hour ago (Oct 27, 2026, 2:50 PM ET)

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In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix recursive locking in RPC handle list access Since commit 305853cce3794 ("ksmbd: Fix race condition in RPC handle list access"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock. This causes hung connections / tasks when a client attempts to open a named pipe. Using Samba's rpcclient tool: $ rpcclient //192.168.1.254 -U user%password $ rpcclient $> srvinfo <connection hung here> Kernel side: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000 Workqueue: ksmbd-io handle_ksmbd_work Call trace: __schedule from schedule+0x3c/0x58 schedule from schedule_preempt_disabled+0xc/0x10 schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8 rwsem_down_read_slowpath from down_read+0x28/0x30 down_read from ksmbd_session_rpc_method+0x18/0x3c ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68 ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228 ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8 create_smb2_pipe from smb2_open+0x10c/0x27ac smb2_open from handle_ksmbd_work+0x238/0x3dc handle_ksmbd_work from process_scheduled_works+0x160/0x25c process_scheduled_works from worker_thread+0x16c/0x1e8 worker_thread from kthread+0xa8/0xb8 kthread from ret_from_fork+0x14/0x38 Exception stack(0x8529ffb0 to 0x8529fff8) The task deadlocks because the lock is already held: ksmbd_session_rpc_open down_write(&sess->rpc_lock) ksmbd_rpc_open ksmbd_session_rpc_method down_read(&sess->rpc_lock) <-- deadlock Adjust ksmbd_session_rpc_method() callers to take the lock when necessary.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Aug 5, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 69674b029002b1d90b655f014bdf64f404efa54d before 5493571f4351f74e11db9943e98a07c56467cf7e; from 6b615a8fb3af0baf8126cde3d4fee97d57222ffc before 1891abe832cbf5a11039e088766131d0f1642d02; from 5cc679ba0f4505936124cd4179ba66bb0a4bd9f3 before 4602b8cee1481dbb896182e5cb1e8cf12910e9e7; from 6bd7e0e55dcea2cf0d391bbc21c2eb069b4be3e1 before 3412fbd81b46b9cfae013817b61d4bbd27e09e36; 305853cce379407090a73b38c5de5ba748893aee builds before 88f170814fea74911ceab798a43cbd7c5599bed4	CNA record
linux linux_kernel linux:linux_kernel	from 6.12.53 before 6.12.55; from 6.17.3 before 6.17.5; 6.18	NVD

References

References

https://git.kernel.org/stable/c/5493571f4351f74e11db9943e98a07c56467cf7e	patch
https://git.kernel.org/stable/c/1891abe832cbf5a11039e088766131d0f1642d02	patch
https://git.kernel.org/stable/c/4602b8cee1481dbb896182e5cb1e8cf12910e9e7	patch
https://git.kernel.org/stable/c/3412fbd81b46b9cfae013817b61d4bbd27e09e36	patch
https://git.kernel.org/stable/c/88f170814fea74911ceab798a43cbd7c5599bed4	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.