{"schemaVersion":3,"id":"CVE-2025-13591","aliases":[],"status":"published","duplicateOf":null,"title":null,"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.","dates":{"published":"2026-10-19T16:45:59.519Z","modified":"2026-10-19T16:45:59.519Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00225,"percentile":0.12388,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-20T00:00:00.000Z","score":0.00225,"percentile":0.12388}],"last30":[{"date":"2026-10-20T00:00:00.000Z","score":0.00225,"percentile":0.12388}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-203","name":"Observable Discrepancy","description":"The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/203.html"}],"affected":[{"vendor":"wso2","product":"email otp authenticator","name":"Email OTP Authenticator","label":"email otp authenticator","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 1.0.18, < 1.0.18.8","noFixRecorded":false,"fixedIn":null},{"text":"≥ 1.0.30, < 1.0.30.5","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.0.18, < 1.0.18.8 | ≥ 1.0.30, < 1.0.30.5","eol":null,"hubHref":"/vendor/wso2/email_otp_authenticator"},{"vendor":"wso2","product":"wso2 carbon abstract otp authenticator","name":"WSO2 Carbon Abstract OTP Authenticator","label":"wso2 carbon abstract otp authenticator","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 1.0.5, < 1.0.5.3","noFixRecorded":false,"fixedIn":null},{"text":"≥ 1.0.10, < 1.0.10.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.0.5, < 1.0.5.3 | ≥ 1.0.10, < 1.0.10.2","eol":null,"hubHref":"/vendor/wso2/wso2_carbon_abstract_otp_authenticator"},{"vendor":"wso2","product":"wso2 identity server","name":"WSO2 Identity Server","label":"wso2 identity server","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 7.0.0, < 7.0.0.134","noFixRecorded":false,"fixedIn":null},{"text":"≥ 7.1.0, < 7.1.0.42","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 7.0.0, < 7.0.0.134 | ≥ 7.1.0, < 7.1.0.42","eol":null,"hubHref":"/vendor/wso2/wso2_identity_server"}],"affectedCount":3,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4583/","label":"security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4583/","hostname":"security.docs.wso2.com","tags":["Vendor Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-19T16:45:59.519Z","label":"Published","detail":"Vulnerability first disclosed.","source":null}],"risk":{"score":21,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T19:59:48.228Z","stale":false,"partial":false}}