Identity Services EngineApplication · Cisco
CVE-2026-20195
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 · uneditedA 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.
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 confidenceThis is an information disclosure vulnerability in Cisco ISE's identity management API where the endpoint returns differentiated error messages for valid versus invalid usernames. An unauthenticated remote attacker can send crafted requests and analyze the varying responses to compile a list of valid user accounts on the system.
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
<= 3.2.0= 3.3.0= 3.4.0= 3.5.0CVSS 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
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Identify Cisco ISE versionLog into the Cisco ISE admin UI and navigate to Administration > System > Deployment, or use the CLI command 'show version' to determine the installed software version.Affected if The installed version is 3.2.0 or earlier, or exactly 3.3.0, 3.4.0, or 3.5.0.
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Determine if the identity management API is exposedCheck if TCP port 443 (HTTPS) is open and accessible from untrusted networks. Review firewall or ACL rules that may restrict access to the ISE admin interface and API endpoints.Affected if The ISE management interface or API port is accessible from untrusted networks without proper filtering.
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Test API endpoint response consistencySend HTTP POST requests to the identity management API endpoint (typically /admin/API/mnt/identity or similar) with a known-valid username and a known-invalid username, then compare the HTTP status codes and response bodies.Affected if The responses differ in content, error messages, or timing between valid and invalid usernames, indicating the vulnerability is present.
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Review current error response configurationAccess Cisco ISE admin UI and navigate to Administration > System > Settings > API Settings, or check the api-security-settings in the ISE CLI, to determine if uniform error responses are enabled.Affected if Uniform error responses are not configured, or the setting to mask username validity is disabled.
A Cisco ISE deployment is affected if it runs an affected version (3.2.0 or earlier, 3.3.0, 3.4.0, or 3.5.0) with the identity management API accessible from untrusted networks and different error messages returned for valid versus invalid usernames.
Generated from the published advisory. Verify against your own configuration.
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 dataConfigure the API endpoint to return uniform responses regardless of username validity, implement rate limiting on authentication-related endpoints, and apply vendor patches when available.
Fix this in Identity Services Engine
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20195 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20195 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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