An issue was discovered in Prosody before 0.11.9. The undocumented dialbackwithoutdialback option in moddialback enables an experimental feature for server-to-server authentication. It does not correctly authenticate remote server certificates, allowing a remote server to impersonate another server (when this option is enabled).

prosody before versions 0.10.2, 0.9.14 is vulnerable to an Authentication Bypass. Prosody did not verify that the virtual host associated with a user session remained the same across stream restarts. A user may authenticate to XMPP host A and migrate their authenticated session to XMPP host B of the same Prosody instance.