Vulnerability Report: GO-2022-0425

• CVE-2021-4239, GHSA-6cr6-fmvc-vw2p, and 1 more
• Affects: github.com/flynn/noise
• Published: Feb 15, 2022
• Modified: May 20, 2024

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.