---
id: CVE-2026-59846
title: 'Libssh: libssh: information disclosure via proxycommand %r username expansion'
summary: >-
  A flaw was found in libssh. A malicious username expanded through %r in
  ProxyCommand handling can inject shell metacharacters, exposing environment
  variables and causing unintended shell behavior.
severity: low
cvss: 3.9
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-78
vendor: Red Hat
product: libssh
affected:
  - libssh (all versions)
  - libssh (all versions)
  - libssh (all versions)
  - libssh (all versions)
  - libssh (all versions)
  - libssh-main (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-07-22T14:03:12.267428Z'
published: '2026-07-21'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T19:28:52.787Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-59846'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:42922'
    label: 'RHSA-2026:42922'
  - url: 'https://access.redhat.com/errata/RHSA-2026:55855'
    label: 'RHSA-2026:55855'
  - url: 'https://access.redhat.com/errata/RHSA-2026:62217'
    label: 'RHSA-2026:62217'
  - url: 'https://access.redhat.com/errata/RHSA-2026:62218'
    label: 'RHSA-2026:62218'
  - url: 'https://access.redhat.com/security/cve/CVE-2026-59846'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2498179'
    label: RHBZ#2498179
tags:
  - cve.org
epss: 0.0012
epssPercentile: 0.01826
ingestedAt: '2026-11-06T20:03:04.274Z'
---

## Overview

A flaw was found in libssh. A malicious username expanded through %r in ProxyCommand handling can inject shell metacharacters, exposing environment variables and causing unintended shell behavior.

## Affected

- `libssh (all versions)`
- `libssh (all versions)`
- `libssh (all versions)`
- `libssh (all versions)`
- `libssh (all versions)`
- `libssh-main (all versions)`

## Remediation

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

### Workarounds

Make sure you are not executing connections with untrusted username inputs.