CallBackery versions before 0.62.0 for Perl store user passwords as unsalted HMAC-SHA1 hashes. Passwords are hashed with hmac_sha1_sum() from Mojo::Util with no key, a single fast SHA-1 HMAC. There is no salt, so equal passwords give equal hashes, and no work factor slows down guessing. An attacker who obtains the user table can recover passwords by fast offline guessing.