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Vulnerability record · CVE-2026-53187 · published 25 June 2026

CVE-2026-53187: Linux kernel out-of-bounds write vulnerability

Linux · Linux Kernel

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.

7.1 CVSS 3.1 High EPSS 0.12% · top 98.2% CWE-787 · Out-of-bounds write
7.1CVSS 3.1 base score
0.12%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
6 Jul 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/0efbb6b54ff56300867027d8e0800d0e32226a20 Patch
https://git.kernel.org/stable/c/323c98a4ff06aa28114f2bf658fb43eb3b536bbc Patch
https://git.kernel.org/stable/c/bd5e818be7964c1689fba2dad9e6bd3a827fee74 Patch

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Source: NIST National Vulnerability Database (record CVE-2026-53187), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.