WordPress announced that WordPress 4.4.1 is now available. It's described specifically as a security release for all previous versions, and they "strongly" encourage you to update your sites ASAP.
The update is a response to WordPress versions 4.4 and earlier being affected by a cross-site scripting vulnerability that could allow sites to be compromised.
In addition to the security fix, the update also includes some additional bug fixes (via WordPress.org Blog):
Emoji support has been updated to include all of the latest emoji characters, including the new diverse emoji! ??????
Some sites with older versions of OpenSSL installed were unable to communicate with other services provided through some plugins.
If a post URL was ever re-used, the site could redirect to the wrong post.
The update fixes 52 WordPress 4.4 bugs in all.
H/T: Marketing Land