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[ CVE-2026-102824 · Published 29 Sep 2026 ]

Russh: Missing X25519 zero-point validation in hybrid ML-KEM key exchange

CVSS 4.3 EPSS <1%Fix available

[ Description ]Official description

Russh is a Rust SSH client and server library. Prior to 0.63.0, the hybrid ML-KEM 768 and X25519 implementation in russh/src/kex/hybrid_mlkem.rs accepts an all-zero 32-byte peer X25519 public key in both server_dh and compute_shared_secret, forcing the X25519 contribution to the combined shared secret to zero. A malicious SSH peer can therefore make the combined secret depend only on ML-KEM, defeating the hybrid exchange's intended fallback protection if ML-KEM is later weakened. This issue is fixed in version 0.63.0.

[ Fixes ]Fixes and patches

  • russh 0.63.0Fixed version · GitHub Advisories · rust package russh: upgrade to 0.63.0 or later (affected < 0.63.0)

[ Packages ]Affected open-source packages

[ References ]References