Dragonfly is an open source P2P-based file distribution and image acceleration system. Versions prior to 2.1.0 contain a server-side request forgery (SSRF) vulnerability that enables users to force DragonFly2’s components to make requests to internal services that are otherwise not accessible to them. The issue arises because the Manager API accepts a user-supplied URL when creating a Preheat job with weak validation, peers can trigger other peers to fetch an arbitrary URL through pieceManager.DownloadSource, and internal HTTP clients follow redirects, allowing a request to a malicious server to be redirected to internal services. This can be used to probe or access internal HTTP endpoints. The vulnerability is fixed in version 2.1.0.