CVE-2025-13166: Username Enumeration via SMS OTP Flow in WSO2 Identity Server Allows User Account Discovery
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.
Affected Software
Event History
Frequently Asked Questions
Which accounts are most readily exposed to enumeration through this issue?
The issue is specifically tied to accounts that have not configured a mobile number. Differences in responses during SMS OTP initiation can allow an unauthenticated attacker to infer whether such usernames are registered.
What does an attacker need to exploit this weakness?
An attacker needs network access to the SMS OTP initiation flow and must be able to observe its responses. No privileges or user interaction are required, but the attack complexity is rated high.
Does this vulnerability directly allow account takeover?
No direct account takeover impact is described. The disclosed usernames may, however, support later brute-force attacks, social-engineering attempts, or information leakage.