Adobe and Microsoft each issued updates today to fix critical security problems with their software. Adobe’s patch tackles 17 flaws in its Acrobat and PDF Reader products. Microsoft released nine update bundles to plug at least 22 security holes in Windows and associated software.

Six of the nine patches Microsoft is pushing out today address flaws the software giant considers “critical,” meaning the vulnerabilities could be exploited by malware or miscreants to break into vulnerable computers remotely without any help from users. The critical updates tackle problems with Internet Explorer, Microsoft Edge, Office and Silverlight, among other components. Links to all of the updates are available here.

As noted by security firm Qualys, several versions of Internet Explorer will get their last security updates this month, including IE 11 on Windows 7 and 10; IE 8, 9 and 10; IE 10 on Server 2012; IE 9 on Vista Service Pack 2 and Server 2008; and IE7 and IE8. If you’re using one of these older versions of IE, consider switching — either to a newer, supported version of IE, or to something less tightly bound to the Windows operating system, such as Google Chrome.

It appears that Microsoft pulled one of the updates (MS16-009) at the last minute, probably due to issues in testing the fix to make sure it won’t interfere with other programs. In any case, if you use Microsoft’s products, take a moment this week to make sure that you’re up to date with these and other available security patches from Redmond.

Separately, Adobe has released critical updates for Adobe Acrobat and Reader. Adobe said it was not aware of any active attacks against the vulnerabilities fixed in this month’s release. Adobe also is phasing out older versions of Acrobat and Reader: As the company notes in this blog post, Adobe Acrobat X and Adobe Reader X are no longer supported.

Adobe Reader comes bundled with a number of third-party software products, but many Windows users may not realize there are alternatives, including some good free ones. For a time I used Foxit Reader, but that program seems to have grown more bloated with each release. My current preference is Sumatra PDF; it is lightweight (about 40 times smaller than Adobe Reader) and quite fast.