Introduction
Enterprise reliance on Microsoft's Remote Desktop Gateway (RD Gateway) has made it a critical infrastructure component. A newly identified vulnerability, CVE-2025-26677, exposes organizations to significant denial-of-service (DoS) risks through uncontrolled resource consumption, potentially halting remote access and administration capabilities.
Affected Systems and Versions
Specific affected versions and configurations have not been detailed in the provided materials. Organizations should consult Microsoft's official advisory for precise version details.
Technical Information
The vulnerability stems from uncontrolled resource consumption (CWE-400). Attackers exploit the RD Gateway's handling of concurrent RDP connection requests by initiating numerous incomplete RDP handshakes. Each handshake consumes system resources, and without proper throttling or resource management, the service quickly becomes overwhelmed, leading to resource exhaustion and denial-of-service.
Attack Vectors and Exploitation Methods
- Attackers perform network scans to identify exposed RD Gateway instances.
- Malicious clients rapidly initiate multiple incomplete RDP handshakes, exhausting memory buffers and thread pools.
- Once resources are depleted, the RD Gateway service rejects new legitimate connection requests, effectively denying service.
Patch Information
Organizations should immediately apply Microsoft's security update KB5050009 to mitigate this vulnerability. Detailed patching steps and direct download links should be obtained from Microsoft's official advisory.
Alternative Mitigations
- Restrict RD Gateway access via firewall rules to trusted IP ranges.
- Implement QoS policies to limit concurrent connections per IP.
Detection Methods
Organizations should monitor for abnormal RDP connection attempts exceeding 500 per minute from single IP addresses. Additionally, monitoring Windows Event Logs for Event ID 26121, indicating RD Gateway resource exhaustion, is recommended.
Vendor Security History
Microsoft has previously addressed similar resource exhaustion vulnerabilities across various products, demonstrating a strong track record of timely patch releases. However, recurring issues suggest ongoing challenges in resource management security.
References
Organizations should prioritize immediate patching and monitoring to safeguard against potential exploitation of CVE-2025-26677.
