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Identity Services EngineApplication · Cisco

CVE-2018-0277

HIGH · 8.6 CVSS v3.0 Published 2018-05-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges 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 Extensible Authentication Protocol-Transport Layer Security (EAP-TLS) certificate validation during EAP authentication for the Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the ISE application server to restart unexpectedly, causing a denial of service (DoS) condition on an affected system. The vulnerability is due to incomplete input validation of the client EAP-TLS certificate. An attacker could exploit this vulnerability by initiating EAP authentication over TLS to the ISE with a crafted EAP-TLS certificate. A successful exploit could allow the attacker to restart the ISE application server, resulting in a DoS condition on the affected system. The ISE application could continue to restart while the client attempts to establish the EAP authentication connection. If an attacker attempted to import the same EAP-TLS certificate to the ISE trust store, it could trigger a DoS condition on the affected system. This exploit vector would require the attacker to have valid administrator credentials. The vulnerability affects Cisco ISE, Cisco ISE Express, and Cisco ISE Virtual Appliance. Cisco Bug IDs: CSCve31857.

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 EAP-TLS certificate validation allows an unauthenticated remote attacker to cause the ISE application server to restart unexpectedly by sending a crafted EAP-TLS certificate during authentication. The root cause is incomplete input validation of the client certificate, leading to a denial of service condition that persists as long as the client attempts to establish the connection.

MitigationApply the Cisco patch for CVE-2018-0277 (CSCve31857) to the affected ISE installations. Until patched, consider restricting network access to ISE EAP authentication endpoints and monitoring for repeated authentication failures indicating exploitation attempts.

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:= 2.0\(0.306\)= 2.0\(1.130\)= 2.1\(0.474\)= 2.2\(0.470\)

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
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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 installation
    On the ISE CLI, run 'show version' or check the admin web interface under Administration > System > Deployment for the ISE server.
    Affected if The system is running Cisco Identity Services Engine.
  2. Check installed ISE version
    Run 'show version' on the ISE CLI or view the version in the admin web interface under Administration > System > About Cisco ISE.
    Affected if The version matches 2.0(0.306), 2.0(1.130), 2.1(0.474), or 2.2(0.470).
  3. Verify EAP-TLS authentication is enabled
    In the ISE admin web interface, go to Policy > Policy Sets or Authentication policies and inspect whether EAP-TLS is configured as an allowed method. On CLI, check with 'show running-config | include eap' or similar authentication configuration.
    Affected if EAP-TLS authentication protocol is enabled in any authentication or policy configuration.
  4. Look for server restart events
    Review ISE logs for application server restarts: check 'show logging applicationise.log' or the Runtime UUID logs around the time of authentication failures. Look for process crash or restart entries.
    Affected if Unexpected application server restarts occur following EAP-TLS authentication attempts.

You are affected if Cisco ISE is installed with version 2.0(0.306), 2.0(1.130), 2.1(0.474), or 2.2(0.470) AND EAP-TLS authentication is enabled, especially if you observe unexplained application server restarts.

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 patch for CVE-2018-0277 (CSCve31857) to the affected ISE installations. Until patched, consider restricting network access to ISE EAP authentication endpoints and monitoring for repeated authentication failures indicating exploitation attempts.

Fix this in Identity Services Engine Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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-2018-0277 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

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