In the Linux kernel’s KVM vSphere interface for s390, a missing radix_tree_preload() call in the _gaccess_shadow_fault() function was identified. The missing call could prevent the routine from advancing correctly, potentially stalling shadow fault processing. Thus, a virtual machine might become non‑responsive due to lost forward progress.

All installations of the Linux kernel that include the KVM vSphere interface (vsie) on s390 architecture are potentially vulnerable. No specific kernel versions are enumerated in the advisory, so any build before the aforementioned commit is at risk.

The EPSS score is reported as < 1% and the vulnerability is not listed in the CISA KEV catalog, indicating that no widespread exploitation has been observed. CVSS score of 5.5 indicates moderate severity. The flaw involves internal kernel code, so an attacker would need to trigger shadow faults from within the host, making remote exploitation unlikely. Nevertheless, because the issue can halt virtual machine operations, it represents a high availability risk for affected systems.