Microsoft has dropped a planned SharePoint patch from tomorrow's Patch Tuesday updates.

The update was to fix an privilege elevation flaw in the collaboration server, which had been rated "important" by Microsoft. This type of flaw can be used to give attackers access to Windows resources that would otherwise be blocked.

Microsoft, which declined to comment further on the matter, did not say when - or if - it would patch the bug. The flaw affects Windows SharePoint Services 3.0 on Windows Server 2003 and Office SharePoint Server 2007.

The company also wouldn't say why it had suddenly decided to pull the patch, but it is not unheard of for Microsoft to pull an update at the last minute because of quality concerns. Microsoft's security updates go through a rigorous testing process to ensure that they don't harm other Windows programs.

According to security vendor McAfee, the delay may give attackers another month to exploit a known SharePoint vulnerability. "There is a yet-to-be patched SharePoint vulnerability that was made public in May this year," the company said in a statement. "The assumption was that Microsoft was going to patch it next week. Now that they have pulled this bulletin, the next possible release date as part of the regular patch cycle is October's Patch Tuesday."

McAfee has not seen any attacks that exploit the flaw in question, however.

Microsoft is still on track to deliver the remaining four security updates tomorrow. Those patches include a critical update for Windows 2000, as well as important patches for Visual Studio, Windows Services for Unix, and the Windows Live and MSN Messenger software.