Microsoft has issued four security patches in its latest monthly update. The May edition of Patch Tuesday features patches for three issues rated ‘critical’ and a fourth rated ‘moderate’.

Experts say the most serious of this month’s Patch Tuesday bulletins includes a critical update in the Jet Data Base Engine, affecting different versions of Windows, including Windows 2000, XP Service Pack 2, XP Professional and Windows Server 2003.

Unlike other vulnerabilities bundled in this month’s patch release, this update repairs security flaws previously been exploited in the wild.

As is customary on patch days, Microsoft released an updated Malicious Software Removal Tool (MSRT) that detects and removes widely circulating malware. Because three of the updates patch critical holes, users and administrators should download and install them immediately, preferably using the Windows built-in automatic update service.