Pac4j v5.1 allows (by default) clients to accept and successfully validate ID Tokens with
none algorithm (i.e., tokens with no signature) which is not secure and violates the OpenID Core Specification. The
none algorithm does not require any signature verification when validating the ID tokens, which allows the attacker to bypass the token validation by injecting a malformed ID token using
none as the value of
alg key in the header with an empty signature value.