image by: heardbleed.com
Recently a massive vulnerability is found in the (open-source) OpenSSL library. Websites starting with https:// were vulnerable due to this bug named as heartbleed (website dedicated to heartbleed FAQs).
OpenSSL is used to keep information and web secure but vulnerability in it allowed attacker to reveal 64kB of memory and this memory handling bug was there for at least 2 years. OpenSSL vulnerabilities