Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
_layouts/Upload.aspx in the Documents module in Microsoft SharePoint before 2010 uses URLs with the same hostname and port number for a web site's primary files and individual users' uploaded files (aka attachments), which allows remote authenticated users to leverage same-origin relationships and conduct cross-site scripting (XSS) attacks by uploading TXT files, a related issue to CVE-2008-5026. NOTE: the vendor disputes the significance of this issue, because cross-domain isolation can be implemented when needed.
CWE-79 - Cross Site Scripting
Cross-Site Scripting, commonly referred to as XSS, is the most dominant class of vulnerabilities. It allows an attacker to inject malicious code into a pregnable web application and victimize its users. The exploitation of such a weakness can cause severe issues such as account takeover, and sensitive data exfiltration. Because of the prevalence of XSS vulnerabilities and their high rate of exploitation, it has remained in the OWASP top 10 vulnerabilities for years.