The vulnerability is a NULL pointer dereference in the KVM s390 implementation of the dat_cond_set_storage_key() routine. When callers pass a NULL value for the oldkey argument, the underlying page_cond_set_storage_key() function dereferences it, resulting in an immediate crash of the kernel. This causes a denial of service by bringing down the virtual machine or the host system that runs KVM on an s390 architecture. The weakness is code that fails to validate a pointer before use, which is typical of a segmentation fault caused by bad input.

All Linux kernel builds that include the KVM s390 subsystem are affected until the patch that guards against NULL dereference is applied. The CVE does not list specific version numbers, so any kernel that has not updated to the fixed code is vulnerable. This includes both upstream Linux and vendor‑supplied distributions that ship the unpatched s390 KVM code.

The flaw does not provide a remote code execution or privilege escalation pathway; it only permits an attacker who can influence the arguments to the storage key routine to crash the kernel. The attack would likely require privileged access to the KVM hypervisor or a malicious guest that can trigger the condition. No EPSS score is available and the vulnerability is not listed in the CISA KEV catalog, implying limited public exploitation data. Nevertheless, because a kernel crash can take a system offline, administrators should treat this as a significant service disruption risk and upgrade promptly.