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

What it is

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.

What to do

Treat this as urgent. Identify every affected system, starting with anything internet-facing, and apply the vendor fix or mitigation within days. If you cannot patch quickly, isolate or disable the affected service and watch for signs of compromise.

Priority

Act now: Patch or mitigate internet-facing systems within days.

Severity (CVSS)

8.6 high

CISA assessment (SSVC)

actively exploited; needs manual effort per target; total control of the affected system

Exploit probability (EPSS, 30 days)

88%, in the top 1% of all CVEs

Added to CISA KEV

25 June 2026

CISA fix-by date

28 June 2026 (US federal agencies; a sensible deadline for everyone)

Ransomware use

Not known

Weakness

CWE-918

References

• NIST NVD entry
• CISA KEV entry
• sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-c
• denizhalil.com/2026/06/12/cve-2026-20230-cisco-unified-cm-ssrf/
• www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20230

Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.