CVE-2025-13591

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

MEDIUM
5.3
CVSS Score
Published: October 19, 2026 at 04:45 PM UTC
Updated: October 20, 2026 at 08:17 PM UTC
3 products affected across 1 vendorIdentity ServerEmail OTP AuthenticatorCarbon Abstract OTP Authenticator

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMWSO2
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-203

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