CVE-2020-28942: Medium severity ejbca vulnerability

An issue exists in PrimeKey EJBCA before 7.4.3 when enrolling with EST while proxied through an RA over the Peers protocol. As a part of EJBCA's domain security model, the peer connector allows the restriction of client certificates (for the RA, not the end user) to a limited set of allowed CAs, thus restricting the accessibility of that RA to the rights it has within a specific role. While this works for other protocols such as CMP, it was found that the EJBCA enrollment over an EST implementation bypasses this check, allowing enrollment with a valid client certificate through any functioning and authenticated RA connected to the CA. NOTE: an attacker must already have a trusted client certificate and authorization to enroll against the targeted CA.