Description
The authentication endpoint of WSO2 Identity Server fails to provide a consistent system response when a username does not exist in the system, allowing attackers to differentiate between valid and invalid usernames. This difference in responses can be leveraged to enumerate existing user accounts.

Successful exploitation enables an attacker to discover valid usernames within the system, significantly increasing the risk of subsequent attacks such as brute force attacks on user credentials, social engineering attacks, and information leakage. The discovered usernames can be used to craft targeted phishing emails or other social engineering campaigns.
Published: 2026-10-19
Score: 5.3 Medium
EPSS: n/a
KEV: No
AI Analysis

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Remediation

Vendor Solution

Follow the instructions given on https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4583/#solution

Tracking

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Advisories

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History

Mon, 19 Oct 2026 17:00:00 +0000

Type Values Removed Values Added
Description The authentication endpoint of WSO2 Identity Server fails to provide a consistent system response when a username does not exist in the system, allowing attackers to differentiate between valid and invalid usernames. This difference in responses can be leveraged to enumerate existing user accounts. Successful exploitation enables an attacker to discover valid usernames within the system, significantly increasing the risk of subsequent attacks such as brute force attacks on user credentials, social engineering attacks, and information leakage. The discovered usernames can be used to craft targeted phishing emails or other social engineering campaigns.
Title Username Enumeration via Authentication Endpoint in WSO2 Identity Server Allows User Account Discovery
First Time appeared Wso2
Wso2 email Otp Authenticator
Wso2 wso2 Carbon Abstract Otp Authenticator
Wso2 wso2 Identity Server
Weaknesses CWE-203
CPEs cpe:2.3:a:wso2:email_otp_authenticator:*:*:*:*:*:*:*:*
cpe:2.3:a:wso2:wso2_carbon_abstract_otp_authenticator:*:*:*:*:*:*:*:*
cpe:2.3:a:wso2:wso2_identity_server:*:*:*:*:*:*:*:*
Vendors & Products Wso2
Wso2 email Otp Authenticator
Wso2 wso2 Carbon Abstract Otp Authenticator
Wso2 wso2 Identity Server
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}


Subscriptions

Wso2 Email Otp Authenticator Wso2 Carbon Abstract Otp Authenticator Wso2 Identity Server
cve-icon MITRE

Status: PUBLISHED

Assigner: WSO2

Published:

Updated: 2026-10-19T16:45:59.519Z

Reserved: 2025-11-24T05:16:09.553Z

Link: CVE-2025-13591

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-19T17:16:59.413

Modified: 2026-10-19T17:16:59.413

Link: CVE-2025-13591

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses