{"cve":"CVE-2021-37151","nvd":{"published":"2021-09-01T13:15:08.367","modified":"2026-06-17T04:00:09.027","status":"Modified","description":"CyberArk Identity 21.5.131, when handling an invalid authentication attempt, sometimes reveals whether the username is valid. In certain authentication policy configurations with MFA, the API response length can be used to differentiate between a valid user and an invalid one (aka Username Enumeration). Response differentiation enables attackers to enumerate usernames of valid application users. Attackers can use this information to leverage brute-force and dictionary attacks in order to discover valid account information such as passwords.","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://www.cyberark.com/products/","https://www.gov.il/en/departments/faq/cve_advisories","https://www.cyberark.com/products/","https://www.gov.il/en/departments/faq/cve_advisories"],"products":["cyberark:identity"],"source":"nvd","synced_at":"2026-10-19T21:21:57.125947417+00:00"},"epss":{"cve":"CVE-2021-37151","score":0.00854,"percentile":0.58334,"date":"2026-10-31"},"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."]}