Frederick Lee, a researcher at insecurity company Fortify, said that the flaw, which affects Ubuntu as well as Debian, had been “seriously underestimated ” as it makes the Secure Sockets Layer (SSL) of the two Linux sustems vulnerable to malicious attack.

“We’re calling this vulnerability ‘insecure randomness’ since it allows an attacker to predict the SSL cryptographic keys used for supposedly secure online transactions,” he said.

Lee reckons that the flaw, which tinkers with the randomness engine used to encrypt secure transactions, could be used to intercept traffic between a user and supposedly secure connection between a user and, for example, an online banking site.