Perspective 5.0.0 contains a cross-site scripting vulnerability in the built-in Debug plugin that allows attackers to inject arbitrary HTML and JavaScript by writing table cell values containing unescaped HTML markup, which are interpolated directly into innerHTML during CSV serialization rendering. Attackers can craft table rows with payloads such as unquoted attribute injections containing event handler attributes that bypass RFC 4180 quoting, since angle brackets and event handler attributes are never escaped before assignment, causing malicious scripts to execute in the embedding page's origin.