CVE-2026-42189

Russh library before version 0.62.5 dispatches channel-scoped Handler callbacks for recipient channel IDs that were never opened or confirmed. The issue is fixed in version 0.62.5.

Russh prior to version 0.62.4 has a denial-of-service vulnerability. An authenticated SSH client can send a pty-req channel request with more than 130 terminal-mode records. The parser in russh/src/server/encrypted.rs stores terminal modes in a fixed 130-entry array but continues increasing the mode count, leading to an out-of-bounds slice and panic before the pty_request handler runs.

Russh is a Rust SSH client & server library. Prior to 0.62.4, an unauthenticated SSH client can cause a denial of service by sending SSH_MSG_KEX_ECDH_INIT with a 32-byte all-zero Q_C value. Curve25519Kex::server_dh in russh/src/kex/curve25519.rs accepts the all-zero peer public value and computes an all-zero shared secret, after which compute_exchange_hash calls encode_mpint in russh/src/kex/mod.rs and indexes beyond the end of the input while skipping leading zero bytes. The resulting panic occurs before authentication and terminates the server key-exchange task. This issue is fixed in version 0.62.4.

Russh is a Rust SSH client & server library. Prior to 0.62.4, a malicious SSH server can crash a russh client session with a malformed KEX_ECDH_REPLY containing a server ephemeral value that is not 32 bytes long. The client-side Curve25519Kex::compute_shared_secret function in russh/src/kex/curve25519.rs passes the decoded exchange.server_ephemeral value to clone_from_slice without validating its length, causing a deterministic panic before the server host key is verified. The panic terminates the spawned client session task and surfaces as a JoinError, while the embedding process normally remains running. This issue is fixed in version 0.62.4.

Vulnerability in the Russh library (Rust SSH client & server) from version 0.34.0 to before 0.61.0. A remote SSH peer can send oversized or malformed length-prefixed fields, causing memory allocation or attempted allocation before rejecting data, potentially leading to denial of service or other issues.

Russh before version 0.61.0 does not strictly enforce SSH identification-string rules. The server-side identification reader uses a permissive path, allowing pre-banner lines from clients and not bounding their number. A remote attacker can hold connection setup resources in the cleartext pre-authentication phase with malformed identification input.

Russh (Rust SSH client & server library) versions 0.37.0 through 0.61.0 contain a vulnerability in the keyboard-interactive authentication path. A malicious SSH server can send USERAUTH_INFO_REQUEST with a controlled prompt count, and the client uses that count directly in Vec::with_capacity(...) before validation, potentially causing memory issues.

Russh before version 0.61.0 has a vulnerability in the server authentication path where internal authentication state is not reset when the username or service changes between requests. This can affect later requests for a different (user, service).

The Russh Rust SSH library versions 0.34.0 through 0.61.1 have a vulnerability related to SSH compression. When compression is enabled, a remote peer can send a compressed packet that decompresses to a much larger size than allowed, leading to resource exhaustion.

A vulnerability in the Russh library (Rust SSH client & server) before version 0.60.3 in the CryptoVec class allows unchecked capacity growth, unchecked length arithmetic, and unsafe allocation/locking paths. Local SSH agents can feed attacker-controlled frame lengths before validation, and in older versions (before 0.58.0) remote SSH traffic also reached CryptoVec through transport and compression buffers.