{"cve":"CVE-2025-13591","nvd":{"published":"2026-10-19T17:16:59.413","modified":"2026-10-20T20:17:10.607","status":"Awaiting Analysis","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.\n\nSuccessful 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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","score":5.3},"cwes":["CWE-203"],"references":["https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4583/"],"products":[],"source":"nvd","synced_at":"2026-10-21T03:56:58.798400159+00:00"},"epss":{"cve":"CVE-2025-13591","score":0.00297,"percentile":0.22171,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}