This advisory announces a vulnerability in the Cucumber Reports Plugin.
Cucumber Reports Plugin disables Content-Security-Policy for archived and workspace files
Jenkins 1.641 and 1.625.3, CloudBees Jenkins Enterprise 1.625.3.1 and 1.609.15.1, and CloudBees Jenkins Enterprise 1.625.3.1 and 1.609.15.1 introduced Content-Security-Policy HTTP headers as protection against Cross-Site Scripting attacks using workspace files and archived artifacts served using DirectoryBrowserSupport (SECURITY-95 ).
The Cucumber Reports Plugin disabled this XSS protection until Jenkins was restarted whenever a Cucumber Report was viewed by any user to work around the Content-Security-Policy limitations.
While disabling this protection mechanism temporarily may be necessary to make plugins work that haven't been adapted to work with the Content-Security-Policy restriction, this should only be done by administrators, as doing so may result in a security issue (see Configuring Content Security Policy on the Jenkins wiki).