All vulnerabilities
CVE-2025-13591

Username Enumeration via Authentication Endpoint in WSO2 Identity Server Allows User Account Discovery

WSO2 WSO2 Identity Server
Open in ThreatlineRecord JSON
CVSS
5.3Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.22%Chance of exploitation activity in the next 30 days, higher than 12% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in7.0.0.134Also 7.1.0.42, 1.0.5.3 and 3 moreCVE List
Published19 Oct 2026Updated 20 Oct 2026CVE List

What fixes it

  • 7.0.0.134WSO2 Identity ServerCVE List
  • 7.1.0.42WSO2 Identity ServerCVE List
  • 1.0.5.3WSO2 Carbon Abstract OTP AuthenticatorCVE List
  • 1.0.10.2WSO2 Carbon Abstract OTP AuthenticatorCVE List
  • 1.0.18.8Email OTP AuthenticatorCVE List
  • 1.0.30.5Email OTP AuthenticatorCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 7

  • WSO2 Identity Serverunknown: all versions before 7.0.0CVE List
  • WSO2 Identity Serveraffected: 7.0.0 before 7.0.0.134CVE List
  • WSO2 Identity Serveraffected: 7.1.0 before 7.1.0.42CVE List
  • WSO2 Carbon Abstract OTP Authenticatoraffected: 1.0.5 before 1.0.5.3CVE List
  • WSO2 Carbon Abstract OTP Authenticatoraffected: 1.0.10 before 1.0.10.2CVE List
  • Email OTP Authenticatoraffected: 1.0.18 before 1.0.18.8CVE List
  • Email OTP Authenticatoraffected: 1.0.30 before 1.0.30.5CVE List

References 1