CVE-2026-53187
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk3th percentile — higher than 3% of all known CVEs
Summary
In the Linux kernel RDMA/core subsystem, the cpu_id attribute from user space is passed to cpumask_test_cpu() without validation, potentially causing an out-of-bounds read of the CPU bitmap. With CONFIG_DEBUG_PER_CPU_MAPS and panic_on_warn enabled, this can lead to a system reboot.
Risk Assessment
The risk includes out-of-bounds memory read and potential denial of service via system reboot triggered by an unprivileged user, impacting service availability.
Recommendation
Apply the kernel patch that validates cpu_id against nr_cpu_ids immediately. If unavailable, restrict access to the RDMA interface for untrusted users.
Original NVD description (English source)
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.