Backdrop CMS version 1.11.0 and earlier contains a Cross Site Scripting (XSS) vulnerability in Sanitization of custom class names used on blocks and l...

Backdrop CMS version 1.11.0 and earlier contains a Cross Site Scripting (XSS) vulnerability in Sanitization of custom class names used on blocks and layouts. that can result in Execution of JavaScript from an unexpected source.. This attack appear to be exploitable via A user must be directed to an affected page while logged in.. This vulnerability appears to have been fixed in 1.11.1 and later.