X-Pack Security versions 6.2.0, 6.2.1, and 6.2.2 are vulnerable to a user impersonation attack via incorrect XML canonicalization and DOM traversal. An attacker might have been able to impersonate a legitimate user if the SAML Identity Provider allows for self registration with arbitrary identifiers and the attacker can register an account which an identifier that shares a suffix with a legitimate account. Both of those conditions must be true in order to exploit this flaw.