Ghost is a Node.js content management system. From 5.94.0 until 6.64.0, when creating a bookmark card, Ghost could store non-image files fetched from an external website as bookmark icons or thumbnails. This allowed any staff user, including Contributors, to host arbitrary HTML on the site's domain, possibly resulting in compromise of other staff users' admin sessions. This issue is fixed in version 6.64.0.
Analyzing vulnerability vectors…