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Identity Services EngineApplication · Cisco

CVE-2019-1851

MEDIUM · 6.8 CVSS v3.1 Published 2019-05-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the External RESTful Services (ERS) API of the Cisco Identity Services Engine (ISE) could allow an authenticated, remote attacker to generate arbitrary certificates signed by the Internal Certificate Authority (CA) Services on ISE. This vulnerability is due to an incorrect implementation of role-based access control (RBAC). An attacker could exploit this vulnerability by crafting a specific HTTP request with administrative credentials. A successful exploit could allow the attacker to generate a certificate that is signed and trusted by the ISE CA with arbitrary attributes. The attacker could use this certificate to access other networks or assets that are protected by certificate authentication.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in Cisco ISE's External RESTful Services (ERS) API contains an RBAC misconfiguration that allows authenticated administrators to generate arbitrary certificates signed by the Internal CA. An attacker with valid admin credentials can craft specific HTTP requests to the ERS API to issue certificates with attacker-controlled attributes, which are trusted by the ISE CA.

MitigationApply the Cisco ISE patch for CVE-2019-1851. Until patched, restrict ERS API access to trusted networks and monitor for anomalous certificate issuance via ISE administrative logging.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Identity Services EngineApplication
Affected:= 2.2\(0.470\)= 2.3\(0.298\)= 2.4\(0.357\)

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Cisco ISE version
    Log into the ISE admin GUI and navigate to Administration > System > Licensing, or use the CLI command 'show version' to determine the installed ISE version.
    Affected if The installed version matches 2.2(0.470), 2.3(0.298), or 2.4(0.357) exactly.
  2. Verify ERS API status
    Navigate to Administration > System > Settings > API Settings in the ISE GUI, or check via CLI with 'show api settings', to confirm whether the External RESTful Services (ERS) API is enabled.
    Affected if ERS API is enabled on the ISE node.
  3. Review certificate issuance logs
    Access ISE operational logs via Administration > Logging > Debug Logs, or query the monitoring database for certificate enrollment events using the ERS API endpoint /ers/config/certificates, focusing on certificates issued by the Internal CA.
    Affected if Unusual or unauthorized certificate issuance records exist, especially certificates with custom attributes requested via ERS API.
  4. Audit admin role permissions
    Review admin user roles and permissions in the GUI under Administration > User Management > Admin Users, or query ERS endpoint /ers/config/administrationuser, to verify which admin roles have ERS certificate management privileges.
    Affected if Admin accounts with ERS access have permissions to request certificates from the Internal CA.

A user is affected if their Cisco ISE version is exactly 2.2(0.470), 2.3(0.298), or 2.4(0.357) AND the ERS API is enabled, allowing authenticated admins to issue arbitrary Internal CA-signed certificates.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco ISE patch for CVE-2019-1851. Until patched, restrict ERS API access to trusted networks and monitor for anomalous certificate issuance via ISE administrative logging.

Fix this in Identity Services Engine Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-1851 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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