The Go SSH library (x/crypto/ssh) by default does not verify host keys, facilitating man-in-the-middle attacks. Default behavior changed in commit e4e2799 to require explicitly registering a hostkey verification mechanism.
The x/crypto/ssh package before 0.0.0-20211202192323-5770296d904e of golang.org/x/crypto allows an attacker to panic an SSH server.
A nil pointer dereference in the golang.org/x/crypto/ssh component through v0.0.0-20201203163018-be400aefbc4c for Go allows remote attackers to cause a denial of service against SSH servers.
golang.org/x/crypto/ssh before 0.0.0-20220314234659-1baeb1ce4c0b in Go through 1.16.15 and 1.17.x through 1.17.8 allows an attacker to crash a server in certain circumstances involving AddHostKey.