In Mellium mellium.im/xmpp through 0.21.0, an attacker capable of spoofing DNS TXT records can redirect a WebSocket connection request to a server under their control without causing TLS certificate verification to fail. This occurs because the wrong host name is selected during this verification.
Affected: Go: mellium.im/xmpp
### Impact
If no TLS configuration is provided by the user, the websocket package constructs its own TLS configuration using recommended defaults. When looking up a WSS endpoint using the DNS TXT record method described in [XEP-0156: Discovering Alternative XMPP Connection Methods](https://xmpp.org/extensions/xep-0156.html) the ServerName field was incorrectly being set to the name of the server returned by the TXT record request, nā¦