Identity Services Engine
CVE-2026-20195: Cisco Identity Services Engine Observable Response Discrepancy Vulnerability
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.
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Cisco Identity Services Engine Software 3.3 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 2 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 1 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 3 | See the advisory |
| Cisco Identity Services Engine Software 3.4 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 4 | See the advisory |
| Cisco Identity Services Engine Software 3.4 Patch 1 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 5 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 6 | See the advisory |
| Cisco Identity Services Engine Software 3.4 Patch 2 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 7 | See the advisory |
| Cisco Identity Services Engine Software 3.4 Patch 3 | See the advisory |
| Cisco Identity Services Engine Software 3.5 | See the advisory |
| Cisco Identity Services Engine Software 3.4 Patch 4 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 8 | See the advisory |
| Cisco Identity Services Engine Software 3.5 Patch 1 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 9 | See the advisory |
| Cisco Identity Services Engine Software 3.4 Patch 5 | See the advisory |
| Cisco Identity Services Engine Software 3.5 Patch 3 | See the advisory |
| Cisco Identity Services Engine Software 3.5 Patch 2 | See the advisory |
| Cisco Identity Services Engine Software 3.3 Patch 10 | See the advisory |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
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.
Exploitation
The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 11 Oct 2026.