---
id: CVE-2025-13591
title: >-
  Username Enumeration via Authentication Endpoint in WSO2 Identity Server
  Allows User Account Discovery
summary: >-
  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 r…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-203
vendor: WSO2
product: WSO2 Identity Server
affected:
  - identity_server >= 7.0.0 < 7.0.0.134
  - identity_server >= 7.1.0 < 7.1.0.42
  - >-
    org.wso2.carbon.identity.auth.otp.commons:org.wso2.carbon.identity.auth.otp.core
    >= 1.0.5 < 1.0.5.3
  - >-
    org.wso2.carbon.identity.auth.otp.commons:org.wso2.carbon.identity.auth.otp.core
    >= 1.0.10 < 1.0.10.2
  - >-
    org.wso2.carbon.identity.local.auth.emailotp:org.wso2.carbon.identity.local.auth.emailotp
    >= 1.0.18 < 1.0.18.8
  - >-
    org.wso2.carbon.identity.local.auth.emailotp:org.wso2.carbon.identity.local.auth.emailotp
    >= 1.0.30 < 1.0.30.5
published: '2026-10-19'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T16:45:59.519Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-13591'
references:
  - url: >-
      https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4583/
tags:
  - cve.org
ingestedAt: '2026-10-19T17:33:42.459Z'
---

## Overview

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.

## Affected

- `identity_server >= 7.0.0 < 7.0.0.134`
- `identity_server >= 7.1.0 < 7.1.0.42`
- `org.wso2.carbon.identity.auth.otp.commons:org.wso2.carbon.identity.auth.otp.core >= 1.0.5 < 1.0.5.3`
- `org.wso2.carbon.identity.auth.otp.commons:org.wso2.carbon.identity.auth.otp.core >= 1.0.10 < 1.0.10.2`
- `org.wso2.carbon.identity.local.auth.emailotp:org.wso2.carbon.identity.local.auth.emailotp >= 1.0.18 < 1.0.18.8`
- `org.wso2.carbon.identity.local.auth.emailotp:org.wso2.carbon.identity.local.auth.emailotp >= 1.0.30 < 1.0.30.5`

## Remediation

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