---
id: CVE-2026-102822
title: Russh is a Rust SSH client and server library
summary: >-
  Russh is a Rust SSH client and server library. Prior to 0.63.1, a connection
  configured to permit mac=none can negotiate it with a MAC-requiring CTR or CBC
  block cipher because the selection logic validates needs_mac() only when MAC
  sele…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-129
vendor: Eugeny
product: russh
affected:
  - russh < 0.63.1
published: '2026-09-29'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T19:17:24.323'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102822'
references:
  - url: >-
      https://github.com/Eugeny/russh/commit/2885385abfee279092a41d80c6cb6ac367353159
    label: security-advisories@github.com
  - url: 'https://github.com/Eugeny/russh/releases/tag/v0.63.1'
    label: security-advisories@github.com
  - url: 'https://github.com/Eugeny/russh/security/advisories/GHSA-p8qx-h547-fjw9'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-29T18:42:35.835Z'
---

## Overview

Russh is a Rust SSH client and server library. Prior to 0.63.1, a connection configured to permit mac=none can negotiate it with a MAC-requiring CTR or CBC block cipher because the selection logic validates needs_mac() only when MAC selection fails. A remote peer can then send a packet with a decrypted length of zero, causing russh/src/cipher/mod.rs to shrink the previously read block before indexing buffer.buffer[16..], which panics and terminates the connection task. This issue is fixed in version 0.63.1.

## Remediation

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