The snow crate before 0.9.5 for Rust, when stateful TransportState is used, allows incrementing a nonce and thereby denying message delivery.

Affected: crates.io: snow

### Impact There was a logic bug where unauthenticated payloads could still cause a nonce increment in snow's internal state. For an attacker with the ability to inject packets into the channel Noise is talking over, this allows a denial-of-service type attack which could prevent communication as it causes the sending and receiving side to be expecting different nonce values than would arrive.

Note that this only affects those who are using the stateful `TransportState`, not those using `StatelessTransportState`.

### Patches This has been patched in version 0.9.5, and all users are recommended to update.

### References There will be a more formal report of this in the near future.

Affected: crates.io: snow

There was a logic bug where unauthenticated payloads could still cause a nonce increment in snow's internal state. For an attacker with privileges to inject packets into the channel over which the Noise session operates, this could allow a denial-of-service attack which could prevent message delivery by sending garbage data.

Note that this only affects those who are using the stateful TransportState, not those using StatelessTransportState.

This has been patched in version 0.9.5, and all users are recommended to update.

Affected: Ubuntu:24.04:LTS: rust-snow, Ubuntu:25.10: rust-snow, Ubuntu:26.04:LTS: rust-snow

The snow crate before 0.9.5 for Rust, when stateful TransportState is used, allows incrementing a nonce and thereby denying message delivery.