Microsoft released just two patches in its monthly Patch Tuesday security update for May.
The relatively light update contrasts with the 17 security bulletins to address 64 vulnerabilities issued in April.
This is in line with the cycle of smaller and larger patches on alternate months, according to security firm Qualys.
MS11-035 is rated as critical and affects the WINS component of Windows 2003 and 2008 server operating systems.
MS11-036 affects Microsoft Office Power Point and is rated important.
The two patches come with Microsoft's improved exploitability index rating.
The original exploitability index is now split into a rating for the most recent version of the software, and an aggregate rating for all older versions, says Qualys.
For an in-depth analysis of this month's Microsoft security update and more information on the new exploitability index, see SearchSecurity.com