CVE-2026-20230: Cisco Unified Communications Manager Server-Side Request Forgery (SSRF) Vulnerability
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.
Other sources
Cisco Unified Communications Manager (Unified CM) and Cisco Unified Communications Manager Session Management Edition (Unified CM SME) contain a server-side request forgery (SSRF) Vulnerability that could allow an unauthenticated, remote attacker to write files to the underlying operating system that could be used later to elevate to root.
— CISA
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Ensure the WebDialer service is disabled (it is enabled only for exploitation; it is disabled by default).
Cisco Unified Communications Manager / Unified CM Session Management Edition (WebDialer service) WebDialer service enabled = disabled - Compensating control
If mitigations are unavailable, discontinue use of Cisco Unified Communications Manager / Unified CM Session Management Edition per the advisory.
- Compensating control
Evaluate each asset’s internet exposure and ensure compliance with CISA BOD 26-04 (Prioritizing Security Updates Based on Risk).
- Compensating control
Follow CISA “Forensics Triage Requirements” guidance in accordance with vendor instructions.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-20230?
The severity of CVE-2026-20230 is classified as high with a score of 8.6.
What type of attacks does CVE-2026-20230 allow?
CVE-2026-20230 allows unauthenticated, remote attackers to conduct server-side request forgery (SSRF) attacks.
Which devices are affected by CVE-2026-20230?
CVE-2026-20230 impacts Cisco Unified Communications Manager and Cisco Unified Communications Manager Session Management Edition.
How can I mitigate the risks associated with CVE-2026-20230?
Mitigation for CVE-2026-20230 involves applying security patches provided by Cisco for the affected systems.
Is user interaction required to exploit CVE-2026-20230?
No, user interaction is not required to exploit CVE-2026-20230 as it can be attacked by unauthenticated remote attackers.