Cisco Unified Communications Manager
Cisco Unified Communications Manager is affected by a high-severity vulnerability (CVE-2026-20230) that is confirmed to be actively exploited in the wild. Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
What is this 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.
How it works
This is classified as Server-Side Request Forgery (SSRF). In plain terms, an attacker could use this flaw in Unified Communications Manager to gain access, disrupt service, or steal data — the exact impact depends on how it’s deployed in your environment.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Mitigations
- Apply the vendor’s security patch or update as soon as it’s available and tested.
- If no patch exists yet, apply the vendor’s temporary workaround.
- Limit network exposure of the affected system until it’s patched.
- Review logs for signs of prior exploitation, especially if it’s flagged for ransomware use.
Recommendations
- Confirm whether Cisco Unified Communications Manager is used anywhere in your environment.
- Patch internet-facing systems first, then internal ones.
- Set a reminder ahead of the remediation deadline so it doesn’t slip.
- Subscribe to the vendor’s security advisories for earlier warning next time.
Compiled from public threat intelligence (CISA Known Exploited Vulnerabilities catalog and the National Vulnerability Database, referenced in 3 public advisories).