A critical vulnerability in a widely used software tool – one quickly exploited in the online game Minecraft – is rapidly emerging as a major threat to organizations around the world.

Log4Shell grants easy access to internal networks, making them susceptible to data theft or loss and malware attacks.

The flaw, nicknamed "Log4Shell", may be the worst computer vulnerability discovered in years. It was uncovered in an open-source logging tool that is ubiquitous in cloud servers and enterprise software used across the industry. Unless it is fixed, it grants criminals, spies and programming novices alike, easy access to internal networks where they can steal valuable data, plant malware, erase crucial information and much more.

Amit Yoran, CEO of the cybersecurity firm Tenable, told the Guardian that Log4Shell was "the single biggest, most critical vulnerability of the last decade" – and possibly the biggest in the history of modern computing.

The vulnerability was rated 10 on a scale of one to 10 by the Apache Software Foundation, which oversees development of the software. Anyone with the exploit can obtain full access to an unpatched computer that uses the software.

In a blog post, Tenable refers to Log4Shell as a "Fukushima moment". According to the firm, "organizations around the world will be dealing with the long-tail consequences of this vulnerability for years to come".

Sources: Sonatype, The Guardian, Tenable