maddy is a composable, all-in-one mail server. Starting with version 0.2.0 and prior to version 0.6.3, maddy allows a full authentication bypass if SASL authorization username is specified when using the PLAIN authentication mechanisms. Instead of validating the specified username, it is accepted as is after checking the credentials for the authentication username. maddy 0.6.3 includes the fix for the bug. There are no known workarounds.
Maddy Mail Server is an open source SMTP compatible email server. Versions of maddy prior to 0.5.4 do not implement password expiry or account expiry checking when authenticating using PAM. Users are advised to upgrade. Users unable to upgrade should manually remove expired accounts via existing filtering mechanisms.