The Linux kernel vulnerability CVE-2026-93112 concerns the bpf_cpumask_populate() function, which writes to its destination using bitmap_copy(). The destination was typed as struct cpumask *, allowing the verifier to accept borrowed cpumask pointers from read-only kernel functions as writable. This improper typing could lead to unintended writes to read-only data. The patch changes the destination type to struct bpf_cpumask *, aligning it with ownership rules of other mutating cpumask kernel functions, preventing misuse of read-only pointers as writable destinations.

This vulnerability allows an attacker with limited privileges (local access with low privileges) to cause integrity and availability impacts by writing to kernel memory areas that should be read-only. This could lead to kernel instability or privilege escalation scenarios. The CVSS score of 7.1 reflects a high severity with local attack vector and no user interaction required.

A fix for this vulnerability has been implemented in the Linux kernel by changing the destination type in bpf_cpumask_populate() to enforce proper ownership and mutability. Users and administrators should apply the official Linux kernel updates that include this fix. Since this is not a cloud service, manual patching is required. Check the Linux kernel vendor advisories for the specific patched versions and apply them promptly.