The so-called "Heartbleed bug" was discovered in OpenSSL software—an encryption service used by around two-thirds of websites to protect information sent to and from Web pages.
Cybercriminals could use the security hole to steal sensitive personal information. Even more worrying is the fact that the code behind the encryption means that even if the bug is fixed, hackers could regain access to the information.
"It's very widespread. It will affect everyone in one way or another," Simon Eappariello, a senior vice president at iboss Network Security, told CNBC in a phone interview.