These are the security changes:
- Blocking server-side request forgery attacks, which could potentially enable an attacker to gain access to a site.
- Disallow contributors from improperly publishing posts, reported by Konstantin Kovshenin, or reassigning the post’s authorship, reported by Luke Bryan.
- An update to the SWFUpload external library to fix cross-site scripting vulnerabilities. Reported by mala and Szymon Gruszecki.
- Prevention of a denial of service attack, affecting sites using password-protected posts.
- An update to an external TinyMCE library to fix a cross-site scripting vulnerability. Reported by Wan Ikram.
- Multiple fixes for cross-site scripting. Reported by Andrea Santese and Rodrigo.
- Avoid disclosing a full file path when a upload fails. Reported by Jakub Galczyk.
Another 12 maintenance related issues have been fixed in the new release. You can check them out here on the WordPress tracker.
Updates should go through without issues on most blogs. I have updated half a dozen blogs so far and none acted up weirdly after the update. All plugins, the theme and the site's functionality worked just like before.
While that has been the case, it is still recommended to make a backup of your blog before you apply the update so that you can roll it back if you run into issues.
You can apply the update directly from the admin dashboard if your blog has been configured this way, or download it from the official website instead to update the blog manually instead.
Please make sure to update as soon as you can, it’s not super awesome to be running around with old and insecure versions of any software.
