A major computer security vulnerability has been discovered – with experts cautiously warning it could potentially affect hundreds of thousands of devices, apps and services, the BBC reports.

However, due to the nature of the bug, it is extremely difficult to know how serious the problem is.

“Many people are running around right now trying to work out if this is truly catastrophic or whether we have dodged a bullet,” said Prof Alan Woodward, a security expect from the University of Surrey.

Google engineers, working with security engineers at Red Hat, have released a patch to fix the problem.

It is now up to manufacturers, and the community behind the Linux operating system, to issue the patch to affected software and devices as soon as possible.

In a blog post explaining the discovery, Google’s team detailed how a flaw in some commonly-used code could be exploited in a way that allows remote access to a devices – be it a computer, internet router, or other connected piece of equipment.

The code can also be within many of the so-called “building blocks” of the web – programming languages such as PHP and Python are affected, as well as systems used when logging in to sites or accessing email.

“It’s not a sky-is-falling scenario,” said Washington D.C-based security researcher Kenneth White.

“But it’s true there’s a very real prospect that a sizable portion of internet-facing services are at risk for hackers to crash, or worse, run remote code to attack others.”

He said that while there is no publicly known attack code using the flaw, it’s a “near certainty” hackers would try to exploit the weakness.