GrowthBook account creation and file upload vulnerability in self-hosted configurations

GrowthBook is an open-source platform for feature flagging and A/B testing. With some self-hosted configurations in versions prior to 2022-08-29, attackers can register new accounts and upload files to arbitrary directories within the container. If the attacker uploads a Python script to the right location, they can execute arbitrary code within the container. To be affected, ALL of the following must be true: Self-hosted deployment (GrowthBook Cloud is unaffected); using local file uploads (as opposed to S3 or Google Cloud Storage); NODE_ENV set to a non-production value and JWT_SECRET set to an easily guessable string like `dev`. This issue is patched in commit 1a5edff8786d141161bf880c2fd9ccbe2850a264 (2022-08-29). As a workaround, set `JWT_SECRET` environment variable to a long random string. This will stop arbitrary file uploads, but the only way to stop attackers from registering accounts is by updating to the latest build.