Yesterday, WordPress released an all new version, i.e., WordPress 4.5.2. This is a security release for the all previous versions, and you should update your site immediately.
To Know more about new things in WordPress 4.5 -> Click Here
WordPress 4.5.1 and earlier are affected by a some vulnerability through Plupload, the third party library WordPress uses for uploading files. WordPress versions 4.2 through 4.5.1 are vulnerable to reflected XSS using specially crafted URIs through MediaElement.js, the third-party library used for media players. MediaElement.js and Plupload have also released updates fixing these issues.
There are multiple widely publicized vulnerabilities in the ImageMagick image processing library, which is used by some hosts and is supported in WordPress.
Please Note: Your site will automatically update to WordPress 4.5.1 if you have enabled automatic background updates. But if you have not yet upgraded your site to WordPress 4.5 then do it now. Please take a backup of your site before updating.
Download The Latest version of WordPress from here.