Cisco released security updates to address vulnerabilities in Cisco IOS XR software. A cyber threat actor could exploit one of these vulnerabilities to take control of an affected device. 

CISA encourages users and administrators to review the following advisories and apply the necessary updates: 

Cisco IOS XR Software for ASR 9000 Series Aggregation Services Routers PPPoE Denial of Service Vulnerability 
Cisco IOS XR Software SSH Privilege Escalation Vulnerability
Cisco IOS XR Software Layer 2 Services Denial of Service Vulnerability