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

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2026-06-25
• EPSS: 88.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-03 · updated 2026-10-07
• Weakness: CWE-918

Description

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.

Affected products

• Cisco Unified Communications Manager: from 14.0 before 14su6; from 15.0 through 15su4a — fixed in 14su6

How to fix

Upgrade to a fixed version: Cisco Unified Communications Manager 14su6. Check the vendor advisory for mitigations.

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-ssrf-cXPnHcW
• https://denizhalil.com/2026/06/12/cve-2026-20230-cisco-unified-cm-ssrf/
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20230

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