curl -- TLS 1.3 session ticket proxy host mixup

Daniel Stenberg reports:

    Enabled by default, libcurl supports the use of TLS 1.3 session
    tickets to resume previous TLS sessions to speed up subsequent
    TLS handshakes.
  

    When using a HTTPS proxy and TLS 1.3, libcurl can confuse session
    tickets arriving from the HTTPS proxy but work as if they arrived
    from the remote server and then wrongly "short-cut" the host
    handshake. The reason for this confusion is the modified sequence
    from TLS 1.2 when the session ids would provided only during the
    TLS handshake, while in TLS 1.3 it happens post hand-shake and
    the code was not updated to take that changed behavior into account.
  

    When confusing the tickets, a HTTPS proxy can trick libcurl to use
    the wrong session ticket resume for the host and thereby circumvent
    the server TLS certificate check and make a MITM attack to be
    possible to perform unnoticed.
  

    This flaw can allow a malicious HTTPS proxy to MITM the traffic.
    Such a malicious HTTPS proxy needs to provide a certificate that
    curl will accept for the MITMed server for an attack to work -
    unless curl has been told to ignore the server certificate check.