Improper Restriction of Excessive Authentication Attempts in GitHub repository mastodon/mastodon prior to 4.0.0.
https://huntr.dev/bounties/2f96f990-01c2-44ea-ae47-58bdb3aa455b
https://github.com/mastodon/mastodon/commit/21fd25a269cca742af431f0d13299e139f267346