A vulnerability in the Linux kernel KVM arm64 subsystem may allow a local attacker to cause a denial of service through improper handling of external aborts.

The vulnerability exists in the KVM arm64 nested virtualization code where kvm_handle_vncr_abort incorrectly assumes that a translation fault always conveys an abort state. This permits an attacker to trigger a kernel panic or instability by inducing specific translation failures, such as addressing a guest frame number outside of memory slots.

The exploitation of this flaw leads to a denial of service condition, resulting in system instability or a complete kernel crash. Given the CVSS score of 7.1, this represents a significant risk to system availability, particularly for environments relying on KVM virtualization for multi-tenant isolation or critical service hosting.

Immediate Action: Update the Linux kernel to version 6.18.40, 7.1.5, or later, where the patch correctly prepares an external abort before returning from the translation function.

Proactive Monitoring: Monitor system logs for kernel panics or repeated KVM-related fault messages that could indicate an attempt to trigger this crash condition.

Compensating Controls: Since this vulnerability requires local access to the host or a guest capable of triggering specific hardware aborts, restrict access to the virtualization host and enforce strict guest configuration policies.

Public Exploit Available: Unknown

This vulnerability presents a clear risk to the availability of virtualized Linux environments. Organizations running KVM on arm64 hardware should prioritize updating their kernel packages to the identified fixed versions immediately to prevent potential system crashes and service interruptions.