Thelia before 3.1.1 contains a stored cross-site scripting vulnerability that allows authenticated back-office administrators with store update permission to inject scripts by uploading unsanitized SVG logo_file or banner_file images. Attackers can upload an SVG with an onload payload served from /admin/store-media/logo or the public cache/images/store/ directory to execute scripts against visitors and higher-privileged administrators.
CWE-79