Out-of-bounds Access Vulnerability in Linux Kernel Affecting CPU Offlining

CVE-2026-64477

What is CVE-2026-64477?

A vulnerability exists within the Linux Kernel where an out-of-bounds access can occur during the offlining of CPUs when SNC (Scale-Out Non-Uniform Memory Access) is enabled. As the architecture updates the cpu_mask in a domain's header to monitor online CPUs, issues arise when the cpu_mask becomes empty. This action prompts the architecture to initiate the offlining process, inadvertently leading to a scenario where the NUMA (Non-Uniform Memory Access) node ID is queried with an incorrect argument, causing the out-of-bounds access. The limbo handler is adjusted to circumvent unnecessary RMID reads when the RMID is ensured to be cleared and further safety checks are added to protect the RMID reader, enhancing the overall security of the system.

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