A defect in the Linux kernel’s KVM S390 PCI subsystem allowed an attempt to enable adapter interrupts via an ioctl call even when the interrupt forwarding had already been enabled. This caused the kernel to overwrite the existing configuration and leak internal resources each time the ioctl was repeated. The resulting resource exhaustion could degrade kernel performance or trigger a crash, effectively providing a denial‑of‑service path for the attacker. The weakness reflects improper handling of resource registration and is a classic case of uncontrolled resource consumption.

The flaw applies to any Linux kernel running the KVM virtual machine monitor with the S390 PCI device support compiled in, regardless of distribution. Affected kernel versions are those deployed prior to the patch that implements the reject logic. The exact affected releases are not enumerated in the data, so any system running a kernel before the provided Git patch should be audited.

The vulnerability does not appear to support remote code execution; instead it offers a local or privilege‑elevated attack surface within the host. Exploitation would require a user with the ability to issue the ioctl on the affected device, typically a privileged guest or admin console. The EPSS score is < 1% and the vulnerability is not listed in CISA's KEV catalog, suggesting no known widespread exploitation. Nonetheless, the inability to apply the patch immediately and the potential for resource exhaustion warrant prompt remediation. The CVSS score is 8.8, indicating a high impact on availability.