CyberArk Identity 21.5.131, when handling an invalid authentication attempt, sometimes reveals whether the username is valid.

published 2021-09-01 5y ago modified 2026-06-17 4mo ago also EUVD-2021-23725

cvss: 5.3; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 58%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

cyberark identity 21.11.133

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Exploit prediction

0.85% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:P/I:N/A:N

Affected products

CyberArk Identity

Classification

Weakness

CWE-203 Observable Discrepancy

References

Sources

CVE List CVE-2021-37151
NVD CVE-2021-37151

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