Linux Kernel up to 6.12.27/6.14.5/6.15-rc4 ksmbd smb2_sess_setup use after free

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.27/6.14.5/6.15-rc4. It has been classified as critical. This affects the function smb2_sess_setup of the component ksmbd. The manipulation leads to use after free. This vulnerability is listed as CVE-2025-37899. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.27/6.14.5/6.15-rc4 and classified as critical. This issue affects the function smb2_sess_setup of the component ksmbd. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in session logoff The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd. The handler for that connection could be in the smb2_sess_setup function which makes use of sess->user.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2025-37899 since 04/16/2025. The exploitation is known to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 12/14/2025).

The vulnerability scanner Nessus provides a plugin with the ID 242283 (Ubuntu 24.04 LTS : Linux kernel (OEM) vulnerabilities (USN-7650-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.28, 6.14.6 or 6.15-rc5 eliminates this vulnerability. Applying the patch d5ec1d79509b3ee01de02c236f096bc050221b7f/2fc9feff45d92a92cd5f96487655d5be23fb7e2b 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 (242283), EUVD (EUVD-2025-15946) and CERT Bund (WID-SEC-2025-1114). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Dell Avamar
• Open Source Linux Kernel
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.14.0
• 6.14.1
• 6.14.2
• 6.14.3
• 6.14.4
• 6.14.5
• 6.15-rc1
• 6.15-rc2
• 6.15-rc3
• 6.15-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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