Yesterday's monthly patch day was a big one, with 17 bulletins fixing a total of 64 security issues in Microsoft products.
Affected applications include Microsoft Windows, Microsoft Office and Internet Explorer.
If you look closer you notice that nine of the 17 patches have a maximum severity rating of critical, the highest possible rating. This means that at least one Microsoft service or product is affected by it this way with others either affected in the same way, to a lesser degree or not at all.
The remaining patches have a rating of important.
When you look at the number of critical vulnerabilities of each individual operating system you will notice that Windows Vista leads the pack with nine critical security vulnerabilities followed by Windows 7 with eight and Windows XP with seven.
The security patches protect the system against remote code execution, information disclosure and elevation of privileges.
You find information about each individual security bulletin, their severity rating and impact over at the Microsoft Security Bulletin Summary for April 2011.
Another interesting read is the risk assessment of April's security updates. Microsoft is aware that some issues are already exploited, while others are likely to be exploited in the coming 30 days.
Windows Updates are as usually available on various channels. Most Windows users are probably using automatic updates to install the new patches.
Those who do not can check manually for updates or visit the Microsoft Download Center to download the patches individually. Another option is to download the April Security Release ISO which contains all Windows patches released in April.
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Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.