Vulnerability · Published Oct 19, 2026 · Assigned by WSO2
CVE-2025-13591Username Enumeration via Authentication Endpoint in WSO2 Identity Server Allows User Account Discovery
Medium 5.3
In plain English
A medium-severity security flaw in Email OTP Authenticator from WSO2. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| WSO2 | WSO2 Identity Server | 7.0.0 – before 7.0.0.1347.1.0 – before 7.1.0.42 |
| WSO2 | WSO2 Carbon Abstract OTP Authenticator | 1.0.5 – before 1.0.5.31.0.10 – before 1.0.10.2 |
| WSO2 | Email OTP Authenticator | 1.0.18 – before 1.0.18.81.0.30 – before 1.0.30.5 |
Weakness: CWE-203 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N