@fastify/multipart is a Fastify plugin for parsing the multipart content-type. Prior to versions 8.3.1 and 9.0.3, the `saveRequestFiles` function does not delete the uploaded temporary files when user cancels the request. The issue is fixed in versions 8.3.1 and 9.0.3. As a workaround, do not use `saveRequestFiles`.
https://github.com/fastify/fastify-multipart/security/advisories/GHSA-27c6-mcxv-x3fh