Medium

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. 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.

Published May 6, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: cisco

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+3
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.28%

ahead of 18% of scored CVEs · Oct 14, 2026

Affects

Cisco

Cisco Identity Services Engine Software and 1 more

CVSS base

5.3

Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cisco Cisco Identity Services Engine Software, Cisco Identity Services Engine).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cisco	Cisco Identity Services Engine Software	version 3.4 Patch 3version 3.3 Patch 2version 3.3 Patch 1version 3.3 Patch 3version 3.4.0version 3.3 Patch 4version 3.4 Patch 1version 3.3 Patch 5 and 13 more version 3.3 Patch 6version 3.4 Patch 2version 3.3 Patch 7version 3.3.0version 3.5.0version 3.4 Patch 4version 3.3 Patch 8version 3.5 Patch 1version 3.3 Patch 9version 3.4 Patch 5version 3.5 Patch 3version 3.5 Patch 2version 3.3 Patch 10	Vulnerable	CVE Program (cve.org) e CISA ADP
Cisco	Identity Services Engine	version 3.3.0-patch9version 3.3.0version 3.3.0-patch1version 3.3.0-patch10version 3.3.0-patch2version 3.3.0-patch3version 3.3.0-patch4version 3.3.0-patch5 and 13 more version 3.3.0-patch6version 3.3.0-patch7version 3.3.0-patch8≤ 3.2.0version 3.4.0version 3.4.0-patch1version 3.4.0-patch2version 3.4.0-patch3version 3.4.0-patch4version 3.4.0-patch5version 3.5.0version 3.5.0-patch1version 3.5.0-patch2	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.3	CVSS 3.1	Medium	3.9	1.4	psirt@cisco.com via NIST National Vulnerability Database
5.3	CVSS 3.1	Medium	—	—	cisco via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-204

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.28%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · cisco/cisco identity services engine software
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 5.3
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
May 6, 2026 · cisco

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-unauth-byp
Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Cisco
every CVE for this vendor

CWE-204
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-76460 Cisco Identity Services Engine Incorrect Use of Privileged APIs Vulnerability KEV 29d
Medium CVE-2026-20146 Cisco Identity Services Engine Path Traversal Vulnerability Jul 15, 2026
High CVE-2026-20190 Cisco Identity Services Engine Information Disclosure Vulnerability Jun 17, 2026
Critical CVE-2026-20181 Cisco Identity Services Engine Remote Code Execution Vulnerability Jun 17, 2026
Medium CVE-2026-20193 Cisco Identity Services Engine Authentication Bypass Vulnerability May 6, 2026
Critical CVE-2026-20186 Cisco Identity Services Engine Multiple Authenticated Remote Code Execution Vulnerability Apr 15, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20195 is "Cisco Identity Services Engine Observable Response Discrepancy Vulnerability", rated Medium. It affects Cisco Identity Services Engine Software (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.28% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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