Misskey is an open source, federated social media platform. Starting in version 12.31.0 and prior to version 2025.4.1, missing validation in `Mk:api` allows malicious AiScript code to access additional endpoints that it isn't designed to have access to. The missing validation allows malicious AiScript code to prefix a URL with `../` to step out of the `/api` directory, thereby being able to make requests to other endpoints, such as `/files`, `/url`, and `/proxy`. Version 2025.4.1 fixes the issue.
https://github.com/misskey-dev/misskey/security/advisories/GHSA-gmq6-738q-vjp2
https://github.com/misskey-dev/misskey/commit/583df3ec63e25a1fd34def0dac13405396b8b663