CVE-2018-18021: Canonical Ubuntu Linux

High severity, CVSS 7.1. EPSS: 0.6% chance of exploitation in the next 30 days.

arch/arm64/kvm/guest.c in KVM in the Linux kernel before 4.18.12 on the arm64 platform mishandles the KVM_SET_ON_REG ioctl. This is exploitable by attackers who can create virtual machines. An attacker can arbitrarily redirect the hypervisor flow of control (with full register control). An attacker can also cause a denial of service (hypervisor panic) via an illegal exception return. This occurs because of insufficient restrictions on userspace access to the core register file, and because PSTATE.M validation does not prevent unintended execution modes.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only
• Debian Debian Linux: version 9.0 only
• Linux Linux Kernel: before 4.18.12 (fixed in 4.18.12)

Published 2018-10-07. Last modified 2026-06-17.