geojson-vt is a JavaScript library for slicing GeoJSON data into vector tiles on the fly, primarily designed to enable rendering and interacting with large geospatial datasets on the browser side (without a server). Prior to version 6.1.1, @maplibre/geojson-vt contains an uncontrolled recursion vulnerability in its GeoJSON conversion logic. When a GeoJSONVT instance is constructed with a deeply nested GeometryCollection object, the mutually recursive functions featureToInternal and convertGeometryCollection in src/convert.ts exhaust the Node.js call stack, causing an unhandled RangeError: Maximum call stack size exceeded that terminates the process. Because the library is widely used in server-side tile services that accept GeoJSON over the network, a remote unauthenticated attacker can trigger a denial-of-service by sending a single crafted payload. No authentication is required, and no non-default library options are needed. This issue has been patched in version 6.1.1.