traQ is a messenger application built for Digital Creators Club traP. Prior to 3.28.3, instances configured with TRAQ_STORAGE_TYPE=local can return user-uploaded SVG or HTML content from the /files/{fileId} retrieval endpoint for direct browser rendering. An attacker with file-upload capability can provide crafted active content and induce another user to open its file URL, causing attacker-controlled JavaScript to execute in the victim's browser. This issue is fixed in version 3.28.3.