Patch is only for Reader 9, so if you’re on 8, you’ll have to upgrade to apply the patch. The dll is about 19 meg too, and even the zip is almost 10 meg. In the event that you do open a bad pdf file, you should see a pop up with the phrase “Insufficient data for an image” and nothing will show up. It may not prevent all attacks on jbig2 – it WILL prevent all current attacks using the method I described, but there may be others.”]
Source: https://blog.talosintelligence.com/2009/02/homebrew-patch-for-adobe-acroreader-9.html