CVE-2025-13591

Medium

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.

SeverityMedium
CVSS5.3
Exploit probability—
ProductWSO2 Identity Server
PublishedOct 19, 2026
First seenOct 19, 2026
Weakness typeCWE-203CWE-203

How to fix

Update
  • WSO2 WSO2 Identity Server7.0.0.134, 7.1.0.42 or later
  • WSO2 WSO2 Carbon Abstract OTP Authenticator1.0.5.3, 1.0.10.2 or later
  • WSO2 Email OTP Authenticator1.0.18.8, 1.0.30.5 or later

Affected products

ProductAffected versionsFixed in
WSO2 WSO2 Identity Server7.0.0 ≤ v < 7.0.0.134, 7.1.0 ≤ v < 7.1.0.427.0.0.134, 7.1.0.42
WSO2 WSO2 Carbon Abstract OTP Authenticator1.0.5 ≤ v < 1.0.5.3, 1.0.10 ≤ v < 1.0.10.21.0.5.3, 1.0.10.2
WSO2 Email OTP Authenticator1.0.18 ≤ v < 1.0.18.8, 1.0.30 ≤ v < 1.0.30.51.0.18.8, 1.0.30.5

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