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CVE-2018-0277· NVD / CVE Program· CNA cisco

A vulnerability in the Extensible Authentication Protocol-Transport Layer Security (EAP-TLS) certificate validation during EAP authenticatio

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.

HighCVSS 8.6 · v3.0—No exploit No fix recorded
Published
May 16, 2018
Updated
Jun 16, 2026
EPSS
2.4% · 83th percentile
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Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
34 / 40 · 8.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Affected systems

VendorProduct
ciscoidentity services engine

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • cisco identity services engine2.0(0.306)
  • cisco identity services engine2.0(1.130)
  • cisco identity services engine2.1(0.474)
  • cisco identity services engine2.2(0.470)

Versions reported by the vendor

Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.

  • n/a Cisco Identity Services Engine

    • Cisco Identity Services Engineaffected

Same product

cisco: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-20281Cisco ISE API Unauthenticated Remote Code Execution VulnerabilityKEV
    99Now
  • CVE-2025-20337Cisco ISE API Unauthenticated Remote Code Execution VulnerabilityKEV
    90Now
  • CVE-2026-76460Cisco Identity Services Engine Authentication Bypass VulnerabilityKEV
    74This week
  • CVE-2025-20282Cisco ISE API Unauthenticated Remote Code Execution Vulnerability
    52Plan
  • CVE-2022-20964A vulnerability in the web-based management interface of Cisco Identity Services Engine could allow an authenticated, remote attacker to inj
    44Plan
  • CVE-2026-20186Cisco Identity Services Engine Multiple Authenticated Remote Code Execution Vulnerability
    41Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

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

nvd-primary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin
override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {  // Left empty for the test environment}

Fixed

kotlin
val client = OkHttpClient.Builder()  .certificatePinner(    CertificatePinner.Builder()      .add("api.sirius.example", "sha256/…")      .build()  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records