Linux Kernel up to 6.12.54/6.17.4/6.18-rc1 ksmbd_session_rpc_method race condition

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CTI Interest Score
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4.9$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.12.54/6.17.4/6.18-rc1. Affected by this issue is the function ksmbd_session_rpc_method. The manipulation leads to race condition. This vulnerability is documented as CVE-2025-40090. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.54/6.17.4/6.18-rc1. It has been rated as critical. This issue affects the function ksmbd_session_rpc_method. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. The summary by CVE is:

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.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-40090 since 04/16/2025. The exploitation is known to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 272092 (Linux Distros Unpatched Vulnerability : CVE-2025-40090), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.55, 6.17.5, 6.18-rc1 or 6.18-rc2 eliminates this vulnerability. Applying the patch 4602b8cee1481dbb896182e5cb1e8cf12910e9e7/3412fbd81b46b9cfae013817b61d4bbd27e09e36/88f170814fea74911ceab798a43cbd7c5599bed4 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (272092) and CERT Bund (WID-SEC-2025-2450). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel
  • Dell NetWorker

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.9

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 272092
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-40090

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.55/6.17.5/6.18-rc1/6.18-rc2
Patch: 4602b8cee1481dbb896182e5cb1e8cf12910e9e7/3412fbd81b46b9cfae013817b61d4bbd27e09e36/88f170814fea74911ceab798a43cbd7c5599bed4

Timelineinfo

04/16/2025 CVE reserved
10/30/2025 +197 days Advisory disclosed
10/30/2025 +0 days VulDB entry created
02/26/2026 +119 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40090 (🔒)
GCVE (CVE): GCVE-0-2025-40090
GCVE (VulDB): GCVE-100-330551
CERT Bund: WID-SEC-2025-2450 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 10/30/2025 14:07
Updated: 02/26/2026 17:00
Changes: 10/30/2025 14:07 (58), 10/30/2025 14:55 (1), 10/30/2025 16:20 (7), 11/01/2025 00:52 (2), 12/21/2025 22:58 (1), 02/15/2026 23:08 (1), 02/26/2026 17:00 (11)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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