Cross-site scripting (XSS) vulnerability in Allegro RomPager before 4.51, as used on the ZyXEL P660HW-D1, Huawei MT882, Sitecom WL-174, TP-LINK TD-8816, and D-Link DSL-2640R and DSL-2641R, when the "forbidden author header" protection mechanism is bypassed, allows remote attackers to inject arbitrary web script or HTML by requesting a nonexistent URI in conjunction with a crafted HTTP Referer header that is not properly handled in a 404 page.  NOTE: there is no CVE for a "URL redirection" issue that some sources list separately.