Sinatra is a domain-specific language for creating web applications in Ruby. An application is vulnerable to a reflected file download (RFD) attack that sets the Content-Disposition header of a response when the filename is derived from user-supplied input.
For Debian 9 stretch, these problems have been fixed in version 1.4.7-5+deb9u2.
We recommend that you upgrade your ruby-sinatra packages.
Further information about Extended LTS security advisories can be found in the dedicated section of our website.