Cisco Unified Communications Manager Server-Side Request Forgery Vulnerability (CVE-2026-20230)

CVE number – CVE-2026-20230

A vulnerability in Cisco Unified Communications Manager (Unified CM) and Cisco Unified Communications Manager Session Management Edition (Unified CM SME) could allow an unauthenticated, remote attacker to conduct server-side request forgery (SSRF) attacks through an affected device.

This vulnerability is due to improper input validation for specific HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to write files to the underlying operating system that could be used later to elevate to root.

Note: Cisco has assigned this security advisory a Security Impact Rating (SIR) of Critical rather than High as the score indicates. The reason is that exploitation of this vulnerability could result in an attacker elevating privileges to root.

Note: To exploit this vulnerability, the WebDialer service must be enabled. WebDialer is disabled by default. This vulnerability affects Cisco Unified CM and Unified CM SME if they have the WebDialer service enabled.

To determine whether WebDialer is enabled, complete the following steps:

1. Log in to the Cisco Unified CM Administration interface.
2. From the Navigation menu, choose Cisco Unified Serviceability and click Go.
3. From the Tools menu, choose Control Center – Feature Services.
4. In the CTI Services section of the page, check whether the current status of the Cisco WebDialer Web Service is Started or Not Running.

If the status is Started, WebDialer is enabled.

To disable WebDialer, complete the following steps:

1. Log in to the Cisco Unified CM Administration interface.
2. From the Navigation menu, choose Cisco Unified Serviceability and click Go.
3. From the Tools menu, choose Service Activation.
4. In the CTI Services section of the page, uncheck the Cisco WebDialer Web Service check box and click Save.

This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-ssrf-cXPnHcW