CVE-2025-13166

Username Enumeration via SMS OTP Flow in WSO2 Identity Server Allows User Account Discovery

Published Sep 15, 2026 CVSS 3.1 · 3.7 Low EPSS < 1% KEV · Not listed
Description
The SMS OTP flow fails to adequately handle error messages, allowing an attacker to infer the existence of registered user accounts based on the responses received during the OTP initiation process.

This weakness can be exploited by an attacker to discover valid usernames within the system. The impact is amplified for accounts that have not configured a mobile number, as the enumeration is specifically tied to this condition. The discovery of these usernames can facilitate subsequent brute force attacks, social engineering attempts, and information leakage, potentially leading to reputational damage, loss of customer trust, and regulatory non-compliance.

Remediation

Vendor Solution

Follow the instructions given on https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4353/#solution

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:wso2:wso2_identity_server:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Wso2
Wso2 wso2 Identity Server
Vendors & Products Wso2
Wso2 wso2 Identity Server
Type Values Removed Values Added
Description The SMS OTP flow fails to adequately handle error messages, allowing an attacker to infer the existence of registered user accounts based on the responses received during the OTP initiation process. This weakness can be exploited by an attacker to discover valid usernames within the system. The impact is amplified for accounts that have not configured a mobile number, as the enumeration is specifically tied to this condition. The discovery of these usernames can facilitate subsequent brute force attacks, social engineering attempts, and information leakage, potentially leading to reputational damage, loss of customer trust, and regulatory non-compliance.
Title Username Enumeration via SMS OTP Flow in WSO2 Identity Server Allows User Account Discovery
Weaknesses CWE-203
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
WSO2
Published
Updated
Sep 15, 2026, 10:15 PM
Reserved
Nov 14, 2025, 6:00 AM
Status
Deferred
Published
Sep 15, 2026, 10:17 AM
Modified
Oct 14, 2026, 7:10 PM