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

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Cisco Unified Communications Manager. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-06-25, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-06-28; treat that as the outer limit, not the target.
• EPSS 88.2%, percentile 99.8: FIRST’s model estimates a 88.2% chance of exploitation activity in the next 30 days, higher than 99.8% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

What it is

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.

CISA’s summary

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.

Weakness type: CWE-918.

Product: Cisco Unified Communications Manager · Assigned by: cisco · Published: 2026-06-03

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-06-25; federal due date 2026-06-28. Known ransomware use: Unknown.
• CISA required action: 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.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 88.20% probability of exploitation activity in the next 30 days; percentile 99.8.

Timeline

• 2026-06-03 — CVE record published by cisco
• 2026-06-25 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-06-28 — CISA remediation deadline for US federal agencies
• 2026-10-07 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (cisco.com) cisco.com

Vulnerability records

1. CVE.org record CVE-2026-20230 cve.org
2. NVD entry CVE-2026-20230 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov
2. Listed in CISA KEV notes (cisa.gov) cisa.gov
3. Listed in CISA KEV notes (cisa.gov) cisa.gov

Other references from the CVE record and advisory

1. cisco-sa-cucm-ssrf-cXPnHcW sec.cloudapps.cisco.com
2. denizhalil.com denizhalil.com

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