CVE-2024-50114 is a high-severity use-after-free vulnerability in the Linux kernel's KVM (Kernel-based Virtual Machine) subsystem specifically affecting the ARM64 architecture. The flaw arises during the teardown process of a virtual CPU (vCPU) when the creation of a vCPU fails late in the initialization sequence, such as when a vCPU with the same ID already exists within the virtual machine (VM). The root cause is improper handling of the MMIO (Memory-Mapped I/O) redistributor unregistration for the failed vCPU. The vulnerability was discovered through syzkaller, a kernel fuzzing tool, which triggered a slab-use-after-free error in the function kvm_put_kvm at kvm_main.c line 5769. The issue originated from a previous code refactor that moved the unregistration logic out of __kvm_vgic_vcpu_destroy() to avoid a lock inversion between srcu and config_lock. However, this change inadvertently left the MMIO redistributor registered for vCPUs that failed creation, leading to a use-after-free when the system later attempts to access freed memory. The fix involves adding a special-case unregistration within __kvm_vgic_vcpu_destroy() for failed vCPUs, ensuring safe teardown without causing lock inversion. This vulnerability impacts Linux kernel versions containing the specified commit hashes prior to the fix and affects ARM64 KVM users. The CVSS v3.1 score is 7.8, reflecting high impact on confidentiality, integrity, and availability with low attack complexity, requiring local privileges but no user interaction. No known exploits are currently in the wild, but the vulnerability could be leveraged by attackers with local access to cause kernel crashes or potentially escalate privileges through memory corruption.

For European organizations, especially those utilizing ARM64-based Linux virtualized environments, this vulnerability poses a significant risk. The KVM subsystem is widely used in cloud infrastructure, data centers, and edge computing deployments. Exploitation could lead to denial of service via kernel crashes or enable privilege escalation attacks, compromising the confidentiality and integrity of sensitive data and critical systems. Organizations running ARM64 Linux kernels in virtualized environments—such as telecom providers deploying ARM-based network functions, cloud service providers offering ARM64 VM instances, or enterprises using ARM64 servers—are particularly vulnerable. The vulnerability could disrupt service availability and lead to data breaches or unauthorized access if exploited. Given the increasing adoption of ARM64 architectures in Europe for energy-efficient computing, the threat surface is expanding. The lack of known public exploits currently limits immediate risk, but the vulnerability's nature and high CVSS score warrant prompt attention to prevent future exploitation.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2024-50114 as soon as vendor updates are available. Until patches are applied, organizations should: 1) Restrict local access to systems running ARM64 KVM to trusted administrators only, minimizing the risk of local exploitation. 2) Monitor kernel logs for unusual KVM or vCPU teardown errors that could indicate attempted exploitation. 3) Employ kernel hardening techniques such as KASLR (Kernel Address Space Layout Randomization) and enable Kernel Page Table Isolation (KPTI) to reduce exploitation feasibility. 4) For cloud providers, isolate ARM64 VM instances and enforce strict tenant separation to limit lateral movement if a VM is compromised. 5) Conduct regular security audits and vulnerability scans focusing on kernel versions and virtualization components. 6) Engage with Linux distribution vendors and subscribe to security advisories to receive timely patch notifications. These steps go beyond generic advice by focusing on access control, monitoring, and environment-specific hardening tailored to ARM64 KVM deployments prevalent in Europe.