CVE-2021-47891: RCE in Unified Remote for Windows

The impact of CVE-2021-47891 is severe. An attacker exploiting this vulnerability can gain complete control over the affected system. This includes the ability to install malware, steal sensitive data, modify system configurations, and potentially pivot to other systems on the network. The attack vector involves sending crafted network packets to port 9512, which is used by Unified Remote for communication. Successful exploitation requires network access to the target machine and knowledge of the protocol. The ease of exploitation, coupled with the potential for complete system compromise, makes this a high-priority vulnerability.

1. Reserved2026-01-18
2. Published2026-01-23
3. Modified2026-04-07
4. EPSS updated2026-03-23

The primary mitigation for CVE-2021-47891 is to upgrade to a patched version of Unified Remote as soon as it becomes available. Until a patch is released, consider isolating affected systems from external networks to prevent potential exploitation. Network segmentation can limit the blast radius if a system is compromised. Firewall rules can be implemented to block inbound traffic to port 9512, preventing external attackers from exploiting the vulnerability. Monitor network traffic for suspicious connections to port 9512. After upgrading, confirm the vulnerability is resolved by attempting to connect to the system with a known malicious packet (if available) and verifying that the connection is rejected.