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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-102824
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-29 19:17:24 UTC
Updated2026-09-29 19:17:24 UTC
DescriptionRussh 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.

Risk And Classification

Primary CVSS: v3.1 4.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-327 | CWE-327 CWE-327: Use of a Broken or Risky Cryptographic Algorithm

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Eugeny Russh affected < 0.63.0 Not specified

References

ReferenceSourceLinkTags
github.com/Eugeny/russh/releases/tag/v0.63.0 [email protected] github.com
github.com/Eugeny/russh/commit/8da8967f196472576b1565d518a0ed60fce60f0c [email protected] github.com
github.com/Eugeny/russh/security/advisories/GHSA-w3jg-pjxf-73p4 [email protected] github.com
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