CVE-2026-21986 is a vulnerability in the core component of Oracle VM VirtualBox, specifically affecting versions 7.1.14 and 7.2.4. The flaw allows an unauthenticated attacker who has local logon access to the infrastructure where VirtualBox runs to compromise the virtualization environment. The attack vector requires local access (AV:L) but no privileges (PR:N) or user interaction (UI:N). The vulnerability results in a complete denial of service (DoS) by causing the VirtualBox process to hang or crash repeatedly, impacting availability (A:H) without affecting confidentiality or integrity. The scope is changed (S:C), meaning the impact extends beyond the vulnerable component to other products relying on VirtualBox. This vulnerability applies only to Windows virtual machines hosted on the affected VirtualBox versions. While no exploits are currently known in the wild, the vulnerability is considered easily exploitable due to the low complexity and lack of required privileges. The CVSS 3.1 base score is 7.1, indicating a high severity primarily due to the potential for widespread service disruption in virtualized environments. The vulnerability was published on January 20, 2026, with no patches or mitigations listed yet, emphasizing the need for immediate attention from affected users.

For European organizations, the primary impact of CVE-2026-21986 is the potential for denial of service on critical virtualized infrastructure running Oracle VM VirtualBox with Windows VMs. This can disrupt business operations, cause downtime, and affect service availability, especially in environments relying heavily on virtualization for production workloads, testing, or development. The scope change indicates that other products dependent on VirtualBox could also be indirectly affected, amplifying the risk. Industries such as finance, healthcare, telecommunications, and government agencies that use Oracle VM VirtualBox for virtualization may face operational interruptions. Additionally, organizations with shared infrastructure or multi-tenant environments could experience cascading effects if an attacker exploits this vulnerability. The requirement for local access limits remote exploitation but does not eliminate risk, as insider threats or compromised credentials could facilitate attacks. The absence of confidentiality and integrity impacts reduces the risk of data breaches but does not diminish the operational impact of availability loss.

1. Immediately identify and inventory all Oracle VM VirtualBox instances running versions 7.1.14 and 7.2.4, focusing on those hosting Windows VMs. 2. Apply vendor patches or updates as soon as they become available from Oracle to remediate the vulnerability. 3. Restrict local access to the infrastructure hosting VirtualBox to trusted personnel only, enforcing strict access controls and monitoring. 4. Implement network segmentation to isolate virtualization hosts from less trusted networks and users. 5. Employ host-based intrusion detection and prevention systems to detect anomalous behavior indicative of exploitation attempts. 6. Regularly audit and review user accounts and permissions to minimize the risk of unauthorized local access. 7. Consider temporary mitigation by limiting the use of affected VirtualBox versions or migrating critical workloads to alternative virtualization platforms until patches are applied. 8. Monitor vendor advisories and threat intelligence feeds for updates on exploit availability and additional mitigation guidance.