Medium · published August 19, 2026
Grav API Plugin is a RESTful API for Grav CMS that provides full headless access to your site's content. Prior to 1.0.2, the Grav API plugin POST /api/v1/media pipeline in HandlesMediaUploads::processUploadedFile() validates an SVG filename extension but does not invoke Security::sanitizeSVG(). An attacker with api.media.write permission can store an SVG containing JavaScript, and the server returns the file as Content-Type: image/svg+xml so the script executes when a victim opens it, allowing session data theft and authenticated actions. This issue is fixed in version 1.0.2.