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A critical vulnerability has been identified in Cisco Unified Communications (UC) products that could allow an unauthenticated remote attacker to execute arbitrary commands on the underlying operating system. Successful exploitation may result in remote code execution as root, leading to full compromise of the affected device. Impacted systems include Unified CM, Unified CM SME, Unified CM IM&P, Unity Connection, and Webex Calling Dedicated Instance. Cisco has confirmed attempted exploitation in the wild, increasing operational risk for exposed deployments.
CVE
CVE-2026-20045
Targeting / Delivery Mechanism
The vulnerability is exploitable over the network via the web-based management interface. An attacker can send a sequence of crafted HTTP requests to a reachable management interface to trigger the flaw. Internet-exposed or poorly segmented deployments present the highest risk.
Execution Technique
Improper validation of user-supplied input in HTTP requests allows arbitrary command execution on the underlying operating system. An attacker can obtain user-level access and subsequently escalate privileges to root.
Persistence / Deployment
With root-level access, an attacker may deploy backdoors, create privileged accounts, modify configurations, or leverage the compromised UC system for lateral movement within the environment.
Operational Impact
Risk is High for large and medium government and business entities and Medium for smaller entities. Successful exploitation enables full system compromise, service disruption, credential theft, and potential pivoting to adjacent systems. Given confirmed exploitation attempts, exposed systems should be treated as high priority.
Validate Integrity
Identify affected Cisco UC products and determine whether management interfaces are externally accessible. Review logs for anomalous HTTP requests, unexpected command execution, privilege escalation events, and configuration changes. Prioritise review of internet-facing or externally accessible systems.
Respond to Confirmed Compromise
Immediately isolate impacted systems and apply Cisco security updates. Conduct forensic analysis for webshells, new root-level accounts, modified services, and altered binaries. Reset administrative and service credentials and rebuild systems if integrity cannot be assured.
Strengthen Preventative Controls
Apply vendor patches following appropriate testing. Restrict management interface exposure using segmentation, access control lists, and VPN access controls. Enforce least privilege for service accounts and implement continuous vulnerability scanning and exploit detection controls.
References
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-voice-rce-mORhqY4b
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-20045
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