Linux Kernel up to 6.18.10/6.19.0 smb recv_done buffer overflow

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.18.10/6.19.0. This vulnerability affects the function recv_done of the component smb. The manipulation results in buffer overflow. This vulnerability is known as CVE-2026-31535. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.10/6.19.0. It has been classified as critical. Affected is the function recv_done of the component smb. 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. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: smb: client: make use of smbdirect_socket.recv_io.credits.available The logic off managing recv credits by counting posted recv_io and granted credits is racy. That's because the peer might already consumed a credit, but between receiving the incoming recv at the hardware and processing the completion in the 'recv_done' functions we likely have a window where we grant credits, which don't really exist. So we better have a decicated counter for the available credits, which will be incremented when we posted new recv buffers and drained when we grant the credits to the peer.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-31535 since 03/09/2026. The exploitability is told to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 07/14/2026).

Upgrading to version 6.18.11 or 6.19.1 eliminates this vulnerability. Applying the patch f664e6e8a81103cb45c8802a9bc7499e0902c458/be8845ad5d6558703d20567d8702155598325db8/9911b1ed187a770a43950bf51f340ad4b7beecba 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 vulnerability database at CERT Bund (WID-SEC-2026-1279). Once again VulDB remains the best source for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel
• Siemens SIMATIC S7

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.19.0

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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