BIT-AUTHENTIK-2023-48228 OAuth2: PKCE can be fully circumvented

authentik is an open-source identity provider. When initialising a oauth2 flow with a codechallenge and codemethod thus requesting PKCE, the single sign-on provider authentik must check if there is a matching and existing codeverifier during the token step. Prior to versions 2023.10.4 and 2023.8....