vBulletin 5.5.4 allows SQL Injection via the ajax/api/hook/getHookList or ajax/api/widget/getWidgetList where parameter.
vBulletin through 5.5.4 mishandles custom avatars.
vBulletin through 5.5.4 mishandles external URLs within the /core/vb/vurl.php file and the /core/vb/vurl directories.
vBulletin 5.5.4 through 5.6.2 allows remote command execution via crafted subWidgets data in an ajax/render/widgettabbedcontainertabpanel request. NOTE: this issue exists because of an incomplete fix for CVE-2019-16759. ALSO NOTE: CVE-2020-7373 is a duplicate of CVE-2020-17496. CVE-2020-17496 is the preferred CVE ID to track this vulnerability.