Uptime Kuma is an open source, self-hosted monitoring tool. From 2.0.0 to 2.1.3 , the GET /api/badge/:id/ping/:duration? endpoint in server/routers/api-router.js does not verify that the requested monitor belongs to a public group. All other badge endpoints check AND public = 1 in their SQL query before returning data. The ping endpoint skips this check entirely, allowing unauthenticated users to extract average ping/response time data for private monitors. This vulnerability is fixed in 2.2.0.