WordPress: Buddypress 2.9.1 - Exceeding the maximum upload size - XSS leading to potential RCE.

Description This report is very similar to https://hackerone.com/bugs?subject=user&reportid=203515 so I will not go into too much details. When uploading a avatar or profile background image thats larger than allowd, the error containing the filename will be output unsanitized leading to XSS...