Advisories for Pypi/Asyncssh package

AsyncSSH 2.22.0 expands the OpenSSH-compatible AuthorizedKeysFile %u token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as AuthorizedKeysFile authorized_keys/%u can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate …

Summary AsyncSSH v2.14.1 and earlier is vulnerable to a novel prefix truncation attack (a.k.a. Terrapin attack), which allows a man-in-the-middle attacker to strip an arbitrary number of messages right after the initial key exchange, breaking SSH extension negotiation (RFC8308) in the process and thus downgrading connection security. Mitigations To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot …

An issue in AsyncSSH v2.14.0 and earlier allows attackers to control the remote end of an SSH client session via packet injection/removal and shell emulation.

An issue in AsyncSSH v2.14.0 and earlier allows attackers to control the extension info message (RFC 8308) via a man-in-the-middle attack.

The SSH server implementation of AsyncSSH does not properly check whether authentication is completed before processing other requests. A customized SSH client can simply skip the authentication step.