Transport Layer Security (TLS) is the protocol mostly used nowadays to protect communications between a client and a server. It cooperates with the Public Key Infrastructure (PKI) to guarantee server authentication by means of an X.509 certificate chain, sent during the TLS handshake, from the server leaf certificate to the root Certification Authority (CA) certificate (trusted a priori). It is the client, who connects to the server, that must validate it. TLS affected all those legal, security and performance use cases that required access to plain HTTP traffic. That led to the introduction of TLS interception solutions. This thesis aims to study the different behavior of TLS clients and TLS interception products facing misconfigured X.509 certificates in a testing/enterprise environment.