CVE-2026-31542

The vulnerability resides in the x86 platform UV subsystem of the Linux kernel. When a processor socket is deconfigured, the kernel incorrectly maps it to SOCK_EMPTY (0xffff). This value is then used when allocating UV hub info structures, leading to a kernel panic because the allocation targets an invalid node.

The panic can be triggered during system initialization or runtime reconfiguration on multi-socket UV platforms with deconfigured sockets. No authentication or special privileges are required, as the condition occurs during normal kernel operations when the system topology changes or boots with deconfigured hardware.

Successful exploitation results in a denial of service (system crash). The fix replaces SOCK_EMPTY with NUMA_NO_NODE, ensuring that hub info structures are allocated on valid memory nodes. Patches have been applied to the stable kernel tree as commits [1][2][3][4].