Russh: client wrong-length X25519 `clone_from_slice` panic (pre-auth DoS)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-73429
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-12 21:17:41 UTC
Updated2026-08-12 21:17:41 UTC
DescriptionRussh is a Rust SSH client & server library. Prior to 0.62.4, a malicious SSH server can crash a russh client session with a malformed KEX_ECDH_REPLY containing a server ephemeral value that is not 32 bytes long. The client-side Curve25519Kex::compute_shared_secret function in russh/src/kex/curve25519.rs passes the decoded exchange.server_ephemeral value to clone_from_slice without validating its length, causing a deterministic panic before the server host key is verified. The panic terminates the spawned client session task and surfaces as a JoinError, while the embedding process normally remains running. This issue is fixed in version 0.62.4.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

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

Problem Types: CWE-704 | CWE-754 | CWE-704 CWE-704: Incorrect Type Conversion or Cast | CWE-754 CWE-754: Improper Check for Unusual or Exceptional Conditions

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Eugeny Russh affected < 0.62.4 Not specified

References

ReferenceSourceLinkTags
github.com/Eugeny/russh/releases/tag/v0.62.4 [email protected] github.com
github.com/Eugeny/russh/commit/a7fc1eb5717264e31c3c5f7dd849b73989a08f3d [email protected] github.com
github.com/Eugeny/russh/security/advisories/GHSA-g9hv-x236-4qp3 [email protected] github.com
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