Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs upon a params parser exception.
access.redhat.com/errata/RHSA-2019:0212
access.redhat.com/errata/RHSA-2019:0315
github.com/advisories/GHSA-mq35-wqvf-r23c
github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2018-11627.yml
github.com/sinatra/sinatra/commit/12786867d6faaceaec62c7c2cb5b0e2dc074d71a
github.com/sinatra/sinatra/issues/1428
nvd.nist.gov/vuln/detail/CVE-2018-11627