---
id: CVE-2026-20195
title: "A vulnerability in an identity management API endpoint of Cisco ISE could allow an unauthenticated, remote attacker to enumerate valid user accounts on an affected device.\r\n\r\nThis vulnerability exists because error messages are observed …"
summary: "A vulnerability in an identity management API endpoint of Cisco ISE could allow an unauthenticated, remote attacker to enumerate valid user accounts on an affected device.\r\n\r\nThis vulnerability exists because error messages are observed …"
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-204
vendor: cisco
product: identity_services_engine
affected:
  - identity_services_engine <= 3.2.0
  - identity_services_engine = 3.3.0
  - identity_services_engine = 3.4.0
  - identity_services_engine = 3.5.0
published: '2026-05-06'
updated: '2026-06-29'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20195'
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-unauth-bypass-uxjRXGpb
    label: psirt@cisco.com
tags:
  - nvd
epss: 0.00275
epssPercentile: 0.20085
ingestedAt: '2026-06-29T15:48:27.661Z'
---

## Overview

A vulnerability in an identity management API endpoint of Cisco ISE could allow an unauthenticated, remote attacker to enumerate valid user accounts on an affected device.

This vulnerability exists because error messages are observed when the affected API endpoint is called. An attacker could exploit this vulnerability by sending a series of crafted requests to the affected endpoint and analyzing the differentiated responses. A successful exploit could allow the attacker to compile a list of valid usernames on an affected system.

## Affected

- `identity_services_engine <= 3.2.0`
- `identity_services_engine = 3.3.0`
- `identity_services_engine = 3.4.0`
- `identity_services_engine = 3.5.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.