The name of the bug found in April 2014 in the publicly available OpenSSL cryptography library was called "Heartbleed". The bug was considered a severe vulnerability and affected millions of websites, including popular social networking, email, and commerce websites. The vulnerability allowed an attacker to gain access to sensitive data, such as passwords and private keys, from affected servers without leaving any trace of their presence. The bug was promptly fixed by the OpenSSL development team, and website administrators were urged to update their systems to protect their users' data.