HashiCorp Vault and Vault Enterprise 1.4.1 and newer allowed the enumeration of users via the LDAP auth method. Fixed in 1.5.6 and 1.6.1.
https://github.com/hashicorp/vault/blob/master/CHANGELOG.md#161
https://discuss.hashicorp.com/t/hcsec-2020-25-vault-s-ldap-auth-method-allows-user-enumeration/18984