When an HTTP server handler sent a 2xx response to an HTTP/1 CONNECT request and returned without hijacking the connection, the server improperly continued to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP.
The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP.
The HTTP/1 server now always closes a connection after responding to a CONNECT request, regardless of the response status.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81744
NOTE: Fixed by: https://github.com/golang/go/commit/e92229e24a387cc006a750af176b07a459ba71a1 (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/087de1ff08ea620ac2f6ae26c939454cb793883a (go1.26.9)