Linux Kernel up to 6.12.52/6.17.2 USB 9pfs Transport Layer usb9pfs_rx_header buffer overflow

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.12.52/6.17.2 and classified as critical. Affected is the function usb9pfs_rx_header of the component USB 9pfs Transport Layer. Performing a manipulation results in buffer overflow. This vulnerability is identified as CVE-2025-40004. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.12.52/6.17.2. This affects the function usb9pfs_rx_header of the component USB 9pfs Transport Layer. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net/9p: Fix buffer overflow in USB transport layer A buffer overflow vulnerability exists in the USB 9pfs transport layer where inconsistent size validation between packet header parsing and actual data copying allows a malicious USB host to overflow heap buffers. The issue occurs because: - usb9pfs_rx_header() validates only the declared size in packet header - usb9pfs_rx_complete() uses req->actual (actual received bytes) for memcpy This allows an attacker to craft packets with small declared size (bypassing validation) but large actual payload (triggering overflow in memcpy). Add validation in usb9pfs_rx_complete() to ensure req->actual does not exceed the buffer capacity before copying data.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-40004 since 04/16/2025. The exploitability is told to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/13/2026).

The vulnerability scanner Nessus provides a plugin with the ID 271675 (Linux Distros Unpatched Vulnerability : CVE-2025-40004), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.53, 6.17.3 or 6.18-rc1 eliminates this vulnerability. Applying the patch 0da18d49f874d444ad83c8a546fa33bfcf2f582c/df8462f0fc045b4475dc494a5787a03c972ba2a2/c04db81cd0288dfc68b7a0f7d09bd49b40bba451 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 CNNVD (CNNVD-202510-2635), Tenable (271675), EUVD (EUVD-2025-35036) and CERT Bund (WID-SEC-2025-2340). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Debian Linux
• Amazon Linux 2
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel

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
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.17.0
• 6.17.1
• 6.17.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

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