There is a possible XSS vulnerability in all rails-html-sanitizer gem versions below 1.0.4 for Ruby. The gem allows non-whitelisted attributes to be present in sanitized output when input with specially-crafted HTML fragments, and these attributes can lead to an XSS attack on target applications. This issue is similar to CVE-2018-8048 in Loofah. All users running an affected release should either upgrade or use one of the workarounds immediately.
Created rubygem-rails-html-sanitizer tracking bugs for this issue:
Affects: fedora-all [bug 1568845]
This issue affects the versions of rubygem-rails-html-sanitizer as shipped with Red Hat CloudForms 4. Red Hat Product Security has rated this issue as having a security impact of Moderate. This vulnerability won't be fixed on CloudForms 4, because it uses libxml 2.9.1 and since the vulnerability requires a libxml >= 2.9.2 in order to be exploitable. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/