CriticalCVE-2026-20230

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

    Published Last modified In CISA KEV since Sources: BSI, SingCERT, pwn.watch, CVE.org

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    What is affected, what to do

    An unauthenticated, remote attacker can exploit a server-side request forgery (SSRF) vulnerability in Cisco Unified Communications Manager (Unified CM) and Cisco Unified Communications Manager Session Management Edition (Unified CM SME) to write files to the underlying operating system, potentially leading to root privilege escalation. The vulnerability, due to improper input validation for specific HTTP requests, is actively exploited in the wild and requires the WebDialer service to be enabled. Affected versions include 14.0 to 14su6 and 15.0 to 15su4a. Immediate patching to the latest available version is critical.

    The vulnerability is being actively exploited; treat it as a priority. Update unified_communications_manager to version 14su6, Unified Communications Manager (CUCM) to version 15SU5. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Cisco Unified Communications Manager eq 14..14
    • Cisco Unified Communications Manager eq 14SU1..14SU1
    • Cisco Unified Communications Manager eq 14SU2..14SU2
    • Cisco Unified Communications Manager eq 14SU3..14SU3
    • Cisco Unified Communications Manager eq 15..15
    • Cisco Unified Communications Manager eq 15SU1..15SU1
    • Cisco Unified Communications Manager eq 14SU4..14SU4
    • Cisco Unified Communications Manager eq 14SU4a..14SU4a
    • Cisco Unified Communications Manager eq 15SU1a..15SU1a
    • Cisco Unified Communications Manager eq 15SU2..15SU2
    • Cisco Unified Communications Manager eq 15.0.1.13010-1..15.0.1.13010-1
    • Cisco Unified Communications Manager eq 15.0.1.13011-1..15.0.1.13011-1
    • Cisco Unified Communications Manager eq 15.0.1.13012-1..15.0.1.13012-1
    • Cisco Unified Communications Manager eq 15.0.1.13013-1..15.0.1.13013-1
    • Cisco Unified Communications Manager eq 15.0.1.13014-1..15.0.1.13014-1
    • Cisco Unified Communications Manager eq 15.0.1.13015-1..15.0.1.13015-1
    • Cisco Unified Communications Manager eq 15.0.1.13016-1..15.0.1.13016-1
    • Cisco Unified Communications Manager eq 15.0.1.13017-1..15.0.1.13017-1
    • Cisco Unified Communications Manager eq 15SU3a..15SU3a
    • Cisco Unified Communications Manager eq 14SU5..14SU5
    • Cisco Unified Communications Manager eq 15SU4..15SU4
    • Cisco Unified Communications Manager eq 15SU4a..15SU4a

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.6

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    8.6

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: BSI, SingCERT, pwn.watch, CVE.org

    88.5 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.77

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    240.77 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: VulnCheck KEV (opens in a new tab), CSA/SingCERT How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    8.6 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    8.6
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    88.5 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.77
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 26 June 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-918

    Response and mitigation

    Why act now?

    Prioritisation rationale

    The flaw is network-reachable without authentication or user interaction and can lead to root on the telephony platform, which is why Cisco rates it Critical despite the lower base score, and its exploitation likelihood sits among the very highest of all tracked CVEs. Attackers value UC platforms as long-lived, poorly monitored footholds into the corporate network and as a source of directory and call data; CISA has not flagged ransomware use so far. WebDialer status is the deciding factor: if it is enabled on a reachable node, treat this as top priority (disable or patch within 24 hours, and for KRITIS operators assess NIS2 reporting obligations if compromise is suspected); if it is verifiably disabled, patch in the regular but near-term maintenance cycle.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory: Identify every Cisco Unified CM and Unified CM SME node (publisher and subscribers) running 14, 14SU1–14SU4a, 15 or 15SU1, e.g. via CLI show version active. On each node check whether the "Cisco WebDialer Web Service" is activated (Cisco Unified Serviceability → Tools → Service Activation / Control Center – Feature Services). Only nodes with WebDialer running are exploitable.
      • Disable WebDialer now wherever it is not business-critical: deactivate the service on all nodes via Service Activation. This is the single most effective stopgap — Cisco states WebDialer is a precondition for exploitation and is off by default.
      • Patch: A fix is available from Cisco. Look up the fixed release or COP file in the Cisco Security Advisory for CVE-2026-20230 and schedule the upgrade (publisher first, then subscribers) in a maintenance window.
      • Restrict reachability: If WebDialer must stay on, immediately limit HTTP/HTTPS access to the CUCM web interfaces (typically TCP 80, 443, 8080, 8443) via ACL/firewall to known client networks and admin jump hosts. Close any internet exposure at once.
      • Start a compromise assessment: For nodes where WebDialer was enabled and reachable from untrusted networks, preserve Tomcat access logs (file get activelog tomcat/logs/* or via RTMT) and engage Cisco TAC for an integrity check. Root-level compromise of an appliance is hard to rule out with built-in tooling alone.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Place the CUCM cluster in a dedicated voice management zone. Permit inbound web access only from defined user VLANs or proxies, and allow /webdialer/ only from networks where click-to-dial clients actually live.
      • Egress filtering (SSRF-specific): Apply default-deny outbound rules on CUCM nodes, allowing only required destinations (cluster peers, NTP, DNS, LDAP/AD, SFTP backup, Smart Licensing, gateways/SBCs). Block outbound HTTP/HTTPS to arbitrary hosts and to management services on other internal systems — this sharply limits what the SSRF can reach.
      • WAF/reverse proxy/IPS: Where a front-end proxy exists, drop requests to /webdialer/ whose parameters contain URLs, IP literals, file://, gopher://, localhost, 127.0.0.1 or traversal sequences (../, %2e%2e). Check Cisco Secure Firewall/Snort vendor signatures for CVE-2026-20230 and enable them in blocking mode once published.
      • IAM/hardening: Expose admin interfaces (CCMAdmin, Serviceability, OS Administration) only through PAM-brokered jump hosts with MFA. After any suspected incident, rotate CUCM application and OS admin passwords, WebDialer/CTI application users and LDAP bind accounts.
      • Configuration governance: Record the WebDialer deactivation in configuration management and add drift checks so the service is not silently re-enabled.

    3. Runbook step 3

      Detection rules

      • Tomcat access logs (via RTMT or remote syslog to SIEM): Requests to /webdialer/ from source IPs outside expected click-to-dial client ranges, and parameters carrying embedded URLs/IPs. SPL example: index=cucm sourcetype=tomcat_access uri_path="/webdialer/*" (uri_query="*http*" OR uri_query="*127.0.0.1*" OR uri_query="*localhost*" OR uri_query="*file:*" OR uri_query="*%2e%2e*").
      • Network telemetry (Zeek/Suricata/firewall): New outbound connections from CUCM IPs to destinations outside the baseline, especially HTTP/HTTPS to internet addresses or internal services CUCM never normally talks to. KQL sketch: CommonSecurityLog | where SourceIP in (cucm_ips) and DestinationPort in (80,443,8080,8443) and DestinationIP !in (allowed_dst).
      • Anomalous response patterns: Bursts of HTTP 200/500 responses or unusually large responses on WebDialer endpoints from a single source — indicative of automated scanning or iterative SSRF probing. Sigma shape: logsource: webserver; detection: uri|contains '/webdialer/' and count by src_ip > N in 5m.
      • Integrity and follow-on activity: Unexpected service restarts, new or modified files surfacing in RTMT trace directories or show diskusage, admin account changes (audit log via file get activelog audit/* or remote audit syslog), and SSH sessions to or from CUCM nodes outside maintenance windows.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    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.

    Source: BSI WID Portal, BSI CSAF, CSA/SingCERT, pwn.watch, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE), cvelistv5

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    CiscoCisco Unified Communications Manager
    • 15SU1
    • 15.0.1.13015-1
    • 14SU5
    • 14
    • 15SU1a
    • 15SU2
    • 15.0.1.13010-1
    • 15SU4
    • 14SU4
    • 14SU3
    • 15.0.1.13012-1
    • 15.0.1.13016-1
    • 15.0.1.13011-1
    • 15
    • 15.0.1.13014-1
    • 14SU4a
    • 14SU2
    • 15SU3a
    • 15.0.1.13017-1
    • 15SU4a
    • 14SU1
    • 15.0.1.13013-1
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    ciscounified_communications_manager
    • 14.0 – < 14su6
    • 15.0 – ≤ 15su4a
    • 14su6
    • —
    CiscoUnified Communications Manager (CUCM)
    • < 15SU5
    • < 14SU6
    • 15SU5
    • 14SU6

    Vendors and products

    Weakness classes (CWE)

    • CWE-918Server-Side Request Forgery (SSRF)

      Base

      The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

      Entry at MITRE CWE-918

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    CSA/SingCERTCritical Vulnerability in Cisco Unified Communications Manager (opens in a new tab)CSA/SingCERTactively exploited
    PoC-in-GitHub (nomi-sec)CVE-2026-20230-Scanner (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-20230 (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    • sec.cloudapps.cisco.comcisco-sa-cucm-ssrf-cXPnHcW
    • denizhalil.com2026/06/12/cve-2026-20230-cisco-unified-cm-ssrfExploit
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20230government-resource
    • pwn.watchpwn.watch: Cisco Unified Communications Manager: Cisco Unified Communications Manager Server-Side Request Forgery (SSRF) Vulnerabilitypwn-watch
    • cisco.comCisco Unified Communications Manager — CVE-2026-20230pwn-watch
    • NVD (NIST)NVD: CVE-2026-20230pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedCisco

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-ssrf-cXPnHcW
      Referenceremoved
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-ssrf-cXPnHcW
      —
      Reference typeremoved
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cucm-ssrf-cXPnHcW Types: Vendor Advisory
      —

      Source identifier: psirt@cisco.com

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: active, automatable: no

      Show 8 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://denizhalil.com/2026/06/12/cve-2026-20230-cisco-unified-cm-ssrf/
      Referenceadded
      —
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20230
      Referenceremoved
      https://denizhalil.com/2026/06/12/cve-2026-20230-cisco-unified-cm-ssrf/
      —
      Referenceremoved
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20230
      —
      Reference typeremoved
      https://denizhalil.com/2026/06/12/cve-2026-20230-cisco-unified-cm-ssrf/ Types: Exploit, Third Party Advisory
      —
      Reference typeremoved
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20230 Types: US Government Resource
      —
      SSVC assessmentremoved
      {"id":"CVE-2026-20230","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-06-03T00:00:00+00:00"}
      —
      SSVC assessmentadded
      —
      {"id":"CVE-2026-20230","role":"CISA Coordinator","options":[{"exploitation":"active"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-06-26T03:55:20.543122Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    3. NVD analysis modifiedNVD

    4. Record modifiedCisco

      Description added or changed

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Cisco Unified Communications Manager
      Cisco Unified Communications Manager
      Descriptionchanged
      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.
      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.

      Source identifier: psirt@cisco.com

    5. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: proof of concept, automatable: no

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://denizhalil.com/2026/06/12/cve-2026-20230-cisco-unified-cm-ssrf/
      SSVC assessmentchanged
      {"id":"CVE-2026-20230","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-06-03T00:00:00+00:00"}
      {"id":"CVE-2026-20230","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-06-24T16:20:41.537697Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    One NVD translation into another language is hidden.

    Linked advisories

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    Badge preview for CVE-2026-20230
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-20230"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-20230.svg?lang=en" alt="CVE-2026-20230 – NEOSEC Intel" height="20"></a>