Steps that you should take:-
You should install fresh updated verion of openssh for windows
Vulnerabliy in SSHv1
In the SSH-1 authentication process, the server generates a 256-bit random number called a challenge. The challenge is then encrypted with the client's public key, so that only the client can decrypt it. The client receives the encrypted challenge and decrypts it. The client returns the challenge response: an MD5 hash of the concatentation of the challenge and the session ID. The server independently computes the expected challenge response by the same formula. If the client's challenge response matches what the server computed, then the server responds that client has successfully authenticated.
Unfortunately, a weakness has been discovered in the formula for computing a session ID from the server's public key. This discovery allows modification of a server's public host key without changing the derived session ID. Furthermore, the modified key is often much weaker than the original, so it is easily factored to create a corresponding private key. This new key pair can be used to negotiate multiple concurrent SSH connections with same the session ID.
The above weakness gives possibility of MIMT .
more over PROTOCOL DOWNGRADE attack is also possible if Server is allowing SSH v1 , In which an attacker can force client to connect to V1 , downgrading the session capabilities
V1 does give allows FORWARD SECRECY , opening off-line attack possibility