CVE-2026-73429

Received Received - Intake

Remote Code Execution in Russh SSH Library

Publication date: 2026-08-12

Last updated on: 2026-08-12

Assigner: GitHub, Inc.

Description

Russh 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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-12

Last Modified

2026-08-12

Generated

2026-08-13

AI Q&A

2026-08-13

EPSS Evaluated

N/A

NVD

CVE-2026-73429

Affected Vendors & Products

Vendor	Product	Version / Range
russh	russh	to 0.62.4 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-754	The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.
CWE-704	The product does not correctly convert an object, resource, or structure from one type to a different type.

Attack-Flow Graph

Executive Summary

This vulnerability affects the Russh SSH library before version 0.62.4. A malicious SSH server can crash a client session by sending a malformed KEX_ECDH_REPLY message with a server ephemeral value not 32 bytes long. The client-side function fails to validate the length before processing, causing a panic and terminating the session task.

Detection Guidance

This vulnerability can be detected by monitoring for crashes in SSH client sessions using the Russh library before version 0.62.4. Check logs for JoinError panics related to Curve25519Kex::compute_shared_secret. No specific commands are provided in the context.

Impact Analysis

If you use a vulnerable version of Russh as an SSH client, a malicious server could crash your client session by sending a specially crafted message. This could disrupt SSH connections but does not allow data theft or code execution.

Mitigation Strategies

Upgrade the Russh library to version 0.62.4 or later to fix the vulnerability. If upgrading is not immediately possible, avoid connecting to untrusted SSH servers until the update is applied.

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