The flaw lies in the SSL protocol, best known as the technology used for secure browsing on Web sites beginning with HTTPS, and lets attackers intercept secure SSL (Secure Sockets Layer) communications between computers using what's known as a man-in-the-middle attack.

Although the flaw can only be exploited under certain circumstances, it could be used to hack into servers in shared hosting environments, mail servers, databases, and many other secure applications, according to Chris Paget, a security researcher who has studied the issue.

"It's a protocol-level flaw." said Paget, the chief technology officer with a security consultancy called H4rdw4re. "There's a whole lot of stuff that's going to have to get fixed on this one: Web browsers, Web servers, Web load balancers, Web accelerators, mail servers, SQL Servers, ODBC drivers, peer-to-peer protocols."

Although an attacker would first need to hack into the victim's network to launch the man-in-the-middle attack, the results would then be devastating -- especially if used in a targeted attack to gain access to a database or a mail server, Paget said.

Because it is so widely used, SSL is constantly under the microscope of security researchers. Late last year, researchers found a way to create fake SSL certificates that would be trusted by any browser, and in August researchers unveiled a handful of new attacks that could compromise SSL traffic. But unlike those attacks, which had to do with the infrastructure used to manage SSL's digital certificates, this latest bug lies in the SSL protocol itself and will be much harder to fix.

Further complicating matters is the fact that the bug was inadvertently disclosed on an obscure mailing list Wednesday, forcing vendors into a mad scramble to patch their products.

The issue was discovered in Auguust by researchers at PhoneFactor, a mobile-phone security company. They had been working for the past two months with a consortium of technology vendors called the ICASI (Industry Consortium for Advancement of Security on the Internet) to coordinate an industry wide fix for the problem, dubbed “Project Mogul."

But their careful plans were thrown into disarray Wednesday when SAP engineer Martin Rex stumbled across the bug on his own. Apparently unaware of the seriousness of the issue, he posted his observations on the issue to an IETF (Internet Engineering Task Force) discussion list. It was then publicized by security researcher HD Moore.