What’s Vulnerable › Vulnerabilities
CVE-2025-13591: Username Enumeration via Authentication Endpoint in WSO2 Identity Server Allows User Account Discovery
- Severity: medium (CVSS 5.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-10-19 · updated 2026-10-20
- Weakness: CWE-203
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.
Affected products
- WSO2 Email OTP Authenticator: from 1.0.18 before 1.0.18.8; from 1.0.30 before 1.0.30.5 — fixed in 1.0.18.8, 1.0.30.5
- WSO2 Identity Server: from 7.0.0 before 7.0.0.134; from 7.1.0 before 7.1.0.42 — fixed in 7.0.0.134, 7.1.0.42
- WSO2 Carbon Abstract OTP Authenticator: from 1.0.5 before 1.0.5.3; from 1.0.10 before 1.0.10.2 — fixed in 1.0.10.2, 1.0.5.3
How to fix
Upgrade to a fixed version: WSO2 Email OTP Authenticator 1.0.18.8, 1.0.30.5; WSO2 Identity Server 7.0.0.134, 7.1.0.42; WSO2 Carbon Abstract OTP Authenticator 1.0.10.2, 1.0.5.3. Check the vendor advisory for mitigations.
References
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