The RC4 stream cipher as used by SSH1 allows remote attackers to modify messages without detection by XORing the original message's cyclic redundancy check (CRC) with the CRC of a mask consisting of all the bits of the original message that were modified.

The IDEA cipher as implemented by SSH1 does not protect the final block of a message against modification, which allows remote attackers to modify the block without detection by changing its cyclic redundancy check (CRC) to match the modifications to the message.

The SSH-1 protocol allows remote servers to conduct man-in-the-middle attacks and replay a client challenge response to a target server by creating a Session ID that matches the Session ID of the target, but which uses a public key pair that is weaker than the target's public key, which allows the attacker to compute the corresponding private key and use the target's Session ID with the compromised key pair to masquerade as the target.

SSH before 2.0 disables host key checking when connecting to the localhost, which allows remote attackers to silently redirect connections to the localhost by poisoning the client's DNS cache.

SSH before 2.0, when using RC4 and password authentication, allows remote attackers to replay messages until a new server key (VK) is generated.

SSH before 2.0, with RC4 encryption and the "disallow NULL passwords" option enabled, makes it easier for remote attackers to guess portions of user passwords by replaying user sessions with certain modifications, which trigger different messages depending on whether the guess is correct or not.

SSH Secure Shell for Servers and SSH Secure Shell for Workstations 2.0.13 through 3.2.1, when running without a PTY, does not call setsid to remove the child process from the process group of the parent process, which allows attackers to gain certain privileges.

Buffer overflow in the URL catcher feature for SSH Secure Shell for Workstations client 3.1 to 3.2.0 allows remote attackers to execute arbitrary code via a long URL.

SSH Secure Shell for Servers 3.0.0 to 3.1.1 allows remote attackers to override the AllowedAuthentications configuration and use less secure authentication schemes (e.g. password) than configured for the server.

SSH 1 through 3, and possibly other versions, allows local users to bypass restricted shells such as rbash or rksh by uploading a script to a world-writeable directory, then executing that script to gain normal shell access.

SSH Secure Shell before 3.2.9 allows remote attackers to cause a denial of service via malformed BER/DER packets.

Race condition in SSH Tectia Server 4.0.3 and 4.0.4 for Unix, when the password change plugin (ssh-passwd-plugin) is enabled, allows local users to obtain the server's private key.

SSH Tectia Server 4.3.1 and earlier, and SSH Secure Shell for Windows Servers, uses insecure permissions when generating the Secure Shell host identification key, which allows local users to access the key and spoof the server.

SSH Tectia Server 5.0.0 (A, F, and T), when allowing host-based authentication only, allows users to log in with the wrong credentials.

Unquoted Windows search path vulnerability in multiple SSH Tectia products, including Client/Server/Connector 5.0.0 and 5.0.1 and Client/Server before 4.4.5, and Manager 2.12 and earlier, when running on Windows, might allow local users to gain privileges via a malicious program file under "Program Files" or its subdirectories.

SSH Tectia Management Agent 2.1.2 allows local users to gain root privileges by running a program called sshd, which is obtained from a process listing when the "Restart" action is selected from the Management server GUI, which causes the agent to locate the pathname of the user's program and restart it with root privileges.

Directory traversal vulnerability in scp in sshd 1.2.xx allows a remote malicious scp server to overwrite arbitrary files via a .. (dot dot) attack.

A race condition in the authentication agent mechanism of sshd 1.2.17 allows an attacker to steal another user's credentials.

SSH 1.2.25 on HP-UX allows access to new user accounts.

In some instances of SSH 1.2.27 and 2.0.11 on Linux systems, SSH will allow users with expired accounts to login.