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.
History

Wed, 30 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 30 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-358
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 29 Sep 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Eugeny
Eugeny russh
Vendors & Products Eugeny
Eugeny russh

Tue, 29 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
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.
Title Russh: Missing X25519 zero-point validation in hybrid ML-KEM key exchange
Weaknesses CWE-327
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-09-29T18:27:41.650Z

Updated: 2026-09-30T20:24:58.381Z

Reserved: 2026-09-29T17:25:25.265Z

Link: CVE-2026-102824

cve-icon Vulnrichment

Updated: 2026-09-30T20:09:35.101Z

cve-icon NVD

Status : Deferred

Published: 2026-09-29T19:17:24.543

Modified: 2026-09-30T21:17:05.920

Link: CVE-2026-102824

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-29T18:27:41Z

Links: CVE-2026-102824 - Bugzilla