Exponent CMS 2.6.0patch2 allows an authenticated user to inject persistent JavaScript code on the "User-Agent" header when logging in. When an administrator user visits the "User Sessions" tab, the JavaScript will be triggered allowing an attacker to compromise the administrator session.
https://github.com/exponentcms/exponent-cms/issues/1546
https://fluidattacks.com/advisories/cobain/
https://exponentcms.lighthouseapp.com/projects/61783/tickets/1461