On Thu, Apr 12, 2018 at 03:04:59PM +0200, Ricardo Wurmus wrote:
> 
> Hi Pierre,
> 
> > Description: 	The RAR uncompression program
> > Upstream URL: 	http://www.rarlab.com/rar_add.htm
> > (Not sure about the licensing of this one: does not look free.  Is there
> > any free way to extract RAR?)
> 
> This is not free software.  There was an unrar package, but it is no
> longer maintained and it had accumulated a few security problems, so we
> decided to remove it.

This discussion was in bug #28972:

https://bugs.gnu.org/28972

Apparently file-roller can handle some RAR files via libarchive.