CVE-2026-102824: Eugeny Russh

Medium severity, CVSS 4.3. EPSS: 0.1% chance of exploitation in the next 30 days.

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.

Affected products

• Eugeny Russh: before 0.63.0 (fixed in 0.63.0)

Published 2026-09-29. Last modified 2026-09-30.