A second patch released last week by Microsoft has caused problems for users, forcing the software company to pull it and, on Monday, release an amended version of the fix.
Bulletin MS13-066 addresses a privately reported flaw, rated 'important', in Active Directory Federation Services (AD FS) that could permit an attacker to obtain information related to the service account being used.
The original patch caused AD FS to stop functioning in some instances, Microsoft said. The new update should eliminate that possibility.
Last week, the company also pulled MS13-061, which addresses three vulnerabilities in Exchange Server. It was scrapped after Microsoft became aware that installing it causes problems. The issues do not occur in Exchange 2007 or 2010 environments, only 2013. Microsoft is still working on a revised fix.