SpriteMotion is a local authoring toolkit. Its web tools are small Python HTTP servers meant for one user on one machine:

All three bind to the loopback interface only and reject requests whose Host or Origin header is not 127.0.0.1:<port> or localhost:<port>, which blocks DNS-rebinding and cross-site requests from web pages (GET, HEAD and POST alike; the pose editor also requires an Origin on POST, and the Studio and pose editor share one guard, common/local_guard.py). State-changing requests accept JSON only, the servers never list a directory and static files are served only from the tool's own folders. They are not designed to be exposed to a network: do not bind them to 0.0.0.0, port-forward them or put them behind a public reverse proxy.

Trusted local user: a few features take a path from the request on purpose, namely Fit Lab /api/assets (import a folder of parts you name) and Content Studio /api/stage (stage into a client folder you name). They assume the person at the keyboard is the one asking; the guard above is what keeps a web page from asking on their behalf.

The tools read and write files under the repository's ignored workspace/ folder, the local asset-pack sidecar (SPRITEMOTION_SIDECAR) and folders you choose. Client staging writes to a new output folder and never modifies the source client installation.

Only the current main branch is supported. There are no released versions yet.

Please report vulnerabilities privately through GitHub's private vulnerability reporting (repository Security tab, Report a vulnerability). Do not open a public issue for a security problem.

Include the affected tool and commit, steps to reproduce and the impact you observed. Do not attach game client files, extracted art or commercial asset-pack content. The maintainer will acknowledge the report in the advisory, land the fix on main and credit you there unless you prefer otherwise.