CVE-2026-35245 Overview
A denial of service vulnerability exists in the Oracle VM VirtualBox product of Oracle Virtualization, specifically affecting the Core component. This vulnerability allows an unauthenticated attacker with network access via the Remote Desktop Protocol (RDP) to cause a complete denial of service condition in Oracle VM VirtualBox, resulting in a hang or frequently repeatable crash of the virtualization software.
Critical Impact
Unauthenticated remote attackers can exploit this vulnerability via RDP to completely crash Oracle VM VirtualBox instances, causing service disruption to all virtualized workloads running on affected hosts.
Affected Products
- Oracle VM VirtualBox version 7.2.6
Discovery Timeline
- 2026-04-21 - CVE CVE-2026-35245 published to NVD
- 2026-04-23 - Last updated in NVD database
Technical Details for CVE-2026-35245
Vulnerability Analysis
This vulnerability is classified under CWE-284 (Improper Access Control), indicating a flaw in how VirtualBox handles access control when processing RDP connections. The vulnerability is easily exploitable and requires no authentication or user interaction, making it particularly dangerous for internet-facing VirtualBox deployments with RDP enabled.
The attack specifically targets the Core component of Oracle VM VirtualBox, which handles fundamental virtualization operations. When exploited, the vulnerability causes a complete denial of service condition, affecting all virtual machines running on the compromised host. This represents a significant availability impact for organizations relying on VirtualBox for development, testing, or production virtualization workloads.
Root Cause
The root cause stems from improper access control in the VirtualBox Core component when handling network-based RDP connections. The vulnerability allows unauthenticated network requests to trigger a condition that leads to application hang or crash. This improper access control failure (CWE-284) enables attackers to send specially crafted RDP traffic that overwhelms or corrupts the internal state of the VirtualBox process.
Attack Vector
The attack is network-based and targets the RDP service exposed by VirtualBox. An attacker does not require any prior authentication or privileges to exploit this vulnerability. The attack can be executed remotely by sending malicious RDP traffic to a VirtualBox instance with the VirtualBox Remote Desktop Extension (VRDE) enabled.
The exploitation requires:
- Network access to the target VirtualBox RDP port (typically port 3389 or custom configured ports)
- No authentication credentials required
- No user interaction required on the target system
The vulnerability manifests when VirtualBox processes certain RDP requests that trigger the improper access control condition. This causes the VirtualBox process to either hang indefinitely or crash repeatedly, denying service to all hosted virtual machines. For detailed technical information, refer to the Oracle Security Alert April 2026.
Detection Methods for CVE-2026-35245
Indicators of Compromise
- Unexpected crashes or hangs of VirtualBox processes (VBoxSVC.exe, VBoxHeadless.exe, or VirtualBox.exe)
- High volume of incoming RDP connection attempts from external sources
- Repeated VirtualBox service restarts in system logs
- Virtual machine availability issues correlated with network activity spikes
Detection Strategies
- Monitor for anomalous RDP traffic patterns targeting VirtualBox VRDE ports
- Configure alerts for VirtualBox process crashes or unexpected terminations
- Implement network intrusion detection rules for malformed RDP packets
- Review VirtualBox logs for repeated connection failures or error conditions
Monitoring Recommendations
- Enable detailed logging for VirtualBox RDP/VRDE connections
- Deploy network monitoring to track connections to VirtualBox RDP ports
- Set up availability monitoring for critical virtual machines to detect service disruptions
- Correlate system event logs with network traffic analysis for comprehensive detection
How to Mitigate CVE-2026-35245
Immediate Actions Required
- Disable VirtualBox Remote Desktop Extension (VRDE) if not required for operations
- Restrict network access to VirtualBox RDP ports using firewall rules
- Implement network segmentation to limit exposure of VirtualBox hosts
- Apply the security patch from Oracle as soon as available
Patch Information
Oracle has addressed this vulnerability in their April 2026 Critical Patch Update. Organizations running Oracle VM VirtualBox version 7.2.6 should upgrade to the patched version as documented in the Oracle Security Alert April 2026.
Review the official Oracle security advisory for specific patch download links and installation instructions. Ensure compatibility testing is performed before deploying patches in production environments.
Workarounds
- Disable VRDE/RDP functionality in VirtualBox if remote access is not operationally required
- Implement strict firewall rules allowing only trusted IP addresses to connect to VirtualBox RDP ports
- Use VPN or SSH tunneling for remote VirtualBox access instead of direct RDP exposure
- Deploy VirtualBox hosts on isolated network segments with limited internet exposure
# Disable VRDE on a specific VM
VBoxManage modifyvm "VM_NAME" --vrde off
# Restrict VirtualBox RDP to specific network interface (localhost only)
VBoxManage modifyvm "VM_NAME" --vrdeaddress 127.0.0.1
# Configure firewall to block external RDP access (Linux iptables example)
iptables -A INPUT -p tcp --dport 3389 -s ! 10.0.0.0/8 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
