---
id: CVE-2026-73430
title: Russh is a Rust SSH client & server library
summary: >-
  Russh is a Rust SSH client & server library. Prior to 0.62.4, an
  unauthenticated SSH client can cause a denial of service by sending
  SSH_MSG_KEX_ECDH_INIT with a 32-byte all-zero Q_C value.
  Curve25519Kex::server_dh in russh/src/kex/curve…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-754
vendor: russh
product: russh
affected:
  - russh < 0.62.4
patched:
  - russh 0.62.4
published: '2026-08-12'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:02:22.660'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73430'
references:
  - url: >-
      https://github.com/Eugeny/russh/commit/a7fc1eb5717264e31c3c5f7dd849b73989a08f3d
    label: security-advisories@github.com
  - url: 'https://github.com/Eugeny/russh/releases/tag/v0.62.4'
    label: security-advisories@github.com
  - url: 'https://github.com/Eugeny/russh/security/advisories/GHSA-5xvq-cp9x-6p6r'
    label: security-advisories@github.com
  - url: 'https://github.com/Eugeny/russh'
tags:
  - nvd
  - osv
  - rust
epss: 0.00597
epssPercentile: 0.46297
aliases:
  - GHSA-5xvq-cp9x-6p6r
ecosystem: rust
ingestedAt: '2026-08-13T19:18:22.025Z'
---

## Overview

Russh is a Rust SSH client & server library. Prior to 0.62.4, an unauthenticated SSH client can cause a denial of service by sending SSH_MSG_KEX_ECDH_INIT with a 32-byte all-zero Q_C value. Curve25519Kex::server_dh in russh/src/kex/curve25519.rs accepts the all-zero peer public value and computes an all-zero shared secret, after which compute_exchange_hash calls encode_mpint in russh/src/kex/mod.rs and indexes beyond the end of the input while skipping leading zero bytes. The resulting panic occurs before authentication and terminates the server key-exchange task. This issue is fixed in version 0.62.4.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-73430)

Affected packages:

- `russh < 0.62.4`

Patched in:

- `russh 0.62.4`

Source: https://osv.dev/vulnerability/GHSA-5xvq-cp9x-6p6r