SChannel in Microsoft Internet Explorer 6 through 11 does not ensure that a server's X.509 certificate is the same during renegotiation as it was before renegotiation, which allows man-in-the-middle attackers to obtain sensitive information or modify TLS session data via a "triple handshake attack," aka "TLS Server Certificate Renegotiation Vulnerability."
https://secure-resumption.com/
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-035