Adobe has said it is working to fix a “critical” security flaw in its Reader, Acrobat and Flash Player software.

It warned that the vulnerability potentially enables hackers to take control of affected computer systems, and that users running Windows, Macintosh or Linux operating systems might all be vulnerable.

The company released details of the glitch in its online security bulletin, in which it said: “This vulnerability could cause a crash and potentially allow an attacker to take control of the affected system.

It added: “There are reports that this vulnerability is being actively exploited in the wild against both Adobe Flash Player, and Adobe Reader and Acrobat.

Graham Cluley, senior technology consultant at security software manufacturer Sophos, told the BBC: “It doesn’t really get any worse than a ‘zero-day’ vulnerability like this.”

He said that hackers might try to gain access to a person’s computer through a booby-trapped PDF document or Flash animation, possibly with the intention of gathering personal information or using the machine to send spam messages.

In recent years, PDFs have become a popular means of sharing documents whose contents are considered largely secure and unalterable.

While it worked to fix the problem, the company suggested upgrading to a pre-release version of the Adobe Flash Player, version 10.1, which it said “does not appear to be vulnerable”.

Mr Cluley said that keeping anti-virus software up to date would also help to avoid problems.

“There has been a long history of vulnerabilities being found in Adobe’s products,” he said.

“This is probably because they are everywhere and omnipresent.”

Adobe estimates that more than 95 per cent of computers worldwide have Flash Player installed.