CVE-2021-4239

The Noise protocol implementation suffers from weakened cryptographic
security after encrypting 2^64 messages, and a potential denial of service
attack. After 2^64 (~18.4 quintillion) messages are encrypted with the
Encrypt function, the nonce counter will wrap around, causing multiple
messages to be encrypted with the same key and nonce. In a separate issue,
the Decrypt function increments the nonce state even when it fails to
decrypt a message. If an attacker can provide an invalid input to the
Decrypt function, this will cause the nonce state to desynchronize between
the peers, resulting in a failure to encrypt all subsequent messages.