CVE-2026-24785CWE-327

Clatter has a PSK Validity Rule Violation issue

High · published January 27, 2026

CVSS v4.0
8.0
EPSS
0%
Percentile
2.8
In the wild
Unconfirmed
What it is

Clatter is a no_std compatible, pure Rust implementation of the Noise protocol framework with post-quantum support. Versiosn prior to2.2.0 have a 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. The issue is fully patched and released in Clatter v2.2.0. The fixed version includes runtime checks to detect offending handshake patterns. As a workaround, avoid using offending `*_psk0` variants of post-quantum patterns. Review custom handshake patterns carefully.

The record
Technical detail
CVSS v4.0
8.0 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U
EPSS
0.00136 · 2.8th percentile
Weakness
CWE-327 · Use of a Broken or Risky Cryptographic Algorithm
Published
2026-01-27T23:38Z
EPSS history
Timeline
  • 27 JAN 23:38Z
    Clatter has a PSK Validity Rule Violation issue
    cvelistv5