Linux Kernel up to 6.18.10/6.19.0 smb smbdirect_socket privilege escalation

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.18.10/6.19.0. This affects the function smbdirect_socket of the component smb. The manipulation leads to an unknown weakness. This vulnerability is traded as CVE-2026-31537. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.10/6.19.0 and classified as critical. This issue affects the function smbdirect_socket of the component smb. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: smb: server: make use of smbdirect_socket.send_io.bcredits It turns out that our code will corrupt the stream of reassabled data transfer messages when we trigger an immendiate (empty) send. In order to fix this we'll have a single 'batch' credit per connection. And code getting that credit is free to use as much messages until remaining_length reaches 0, then the batch credit it given back and the next logical send can happen.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-31537 since 03/09/2026. 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 07/14/2026).

The vulnerability scanner Nessus provides a plugin with the ID 310323 (Linux Distros Unpatched Vulnerability : CVE-2026-31537), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.18.11 or 6.19.1 eliminates this vulnerability. Applying the patch 5ef18a2e66f2f33fdac64437bddfb9fe6389fdc7/79242e7b6bc63efec28b7c235bc320806afce6c0/34abd408c8ba24d7c97bd02ba874d8c714f49db1 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 (310323) and CERT Bund (WID-SEC-2026-1279). Statistical analysis made it clear that VulDB provides the best quality 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

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion