Linux Kernel up to 6.18.35/7.0.12 RDMA cpumask_test_cpu cpu_id out-of-bounds

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.35/7.0.12. It has been rated as critical. This issue affects the function cpumask_test_cpu of the component RDMA. The manipulation of the argument cpu_id leads to out-of-bounds. This vulnerability is documented as CVE-2026-53187. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.35/7.0.12. It has been rated as problematic. This issue affects the function cpumask_test_cpu of the component RDMA. The manipulation of the argument cpu_id with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: RDMA/core: Validate cpu_id against nr_cpu_ids in DMAH alloc The cpu_id attribute supplied by user space through UVERBS_ATTR_ALLOC_DMAH_CPU_ID is passed directly to cpumask_test_cpu() without first verifying that the value is within the valid CPU range. Passing such untrusted data to cpumask_test_cpu() may lead to an out-of-bounds read of the underlying cpumask bitmap: the helper expands to a test_bit() that indexes the bitmap by cpu_id / BITS_PER_LONG with no bound check. In addition, on kernels built with CONFIG_DEBUG_PER_CPU_MAPS it trips the WARN_ON_ONCE() in cpumask_check(); combined with panic_on_warn this turns a bad user input into a machine reboot. Reject any cpu_id that is not smaller than nr_cpu_ids with -EINVAL before it is used. Reported by Smatch.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-53187 since 06/09/2026. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 323569 (Linux Distros Unpatched Vulnerability : CVE-2026-53187), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.18.36 or 7.0.13 eliminates this vulnerability. Applying the patch bd5e818be7964c1689fba2dad9e6bd3a827fee74/0efbb6b54ff56300867027d8e0800d0e32226a20/323c98a4ff06aa28114f2bf658fb43eb3b536bbc 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 (323569) and CERT Bund (WID-SEC-2026-2077). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 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
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9
• 7.0.10
• 7.0.11
• 7.0.12

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Entryinfo

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

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