GHSA-253q-9q78-63x4

### Impact Protocol compliance vulnerability. The library allowed post-quantum handshake patterns that violated the PSK validity rule (Noise Protocol Framework Section 9.3). This could allow PSK-derived keys to be used for encryption without proper randomization by self-chosen ephemeral randomness, weakening security guarantees and potentially allowing catastrophic key reuse. Affected default patterns include `noise_pqkk_psk0`, `noise_pqkn_psk0`, `noise_pqnk_psk0`, `noise_pqnn_psk0`, and some hybrid variants. Users of these patterns may have been using handshakes that do not meet the intended security properties. ### Patches The issue is fully patched and released in Clatter v2.2.0. The fixed version includes runtime checks to detect offending handshake patterns. ### Workarounds Avoid using offending `*_psk0` variants of post-quantum patterns. Review custom handshake patterns carefully. ### Resources * [PSK validity rule](https://noiseprotocol.org/noise.html#validity-rule)