{"schemaVersion":3,"id":"CVE-2020-13998","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Citrix XenApp 6.5, when 2FA is enabled, allows a remote unauthenticated attacker to ascertain whether a user exists on the server, because the 2FA error page only occurs after a valid username is entered. NOTE: This vulnerability only affects products that are no longer supported by the maintainer","dates":{"published":"2020-06-11T01:59:35.000Z","modified":"2024-08-04T12:32:14.840Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.5,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.5,"severity":"high","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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},{"version":"2.0","versionLabel":"v2.0","source":"NVD","score":4.3,"severity":"medium","vector":"AV:N/AC:M/Au:N/C:P/I:N/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.01389,"percentile":0.71881,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.01389},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.01389,"percentile":0.71881}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.01389,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.01389,"percentile":0.71881}]},"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"},{"id":"CWE-639","name":"Authorization Bypass Through User-Controlled Key","description":"The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/639.html"}],"affected":[{"vendor":"citrix","product":"xenapp","name":"xenapp","label":"xenapp","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"6.5.0.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"6.5.0.0","eol":null,"hubHref":"/vendor/citrix/xenapp"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://gist.github.com/kampji/11e259d68ad98a6f0f898132f1961a96","label":"gist.github.com/kampji/11e259d68ad98a6f0f898132f1961a96","hostname":"gist.github.com","tags":["X Refsource MISC","Third Party Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2020-06-11T01:59:35.000Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2024-08-04T12:32:14.840Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":30,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-19T14:46:21.318Z","stale":false,"partial":false}}