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.
https://www.debian.org/security/2018/dsa-4216
https://prosody.im/security/advisory_20180531/
https://issues.prosody.im/1147