Read the official Contao announcements.
TYPOlight 2.5.1 is available
by Leo Feyer – Announcements
TYPOlight version 2.5.1 is available. The maintenance release includes some important bug fixes and a couple of small improvements. Amongst others, it fixes the issue with missing permissions when creating new news items or events as a normal user and the phpmailer "carbon copy bug".
Download this release from github.com.