---
id: CVE-2026-59851
title: 'Libssh: libssh: authentication bypass via missing gssapi principal check'
summary: >-
  A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the
  gssapi-keyex path does not verify whether the authenticated Kerberos principal
  is authorized for the requested local user, allowing authenticated clients to
  log i…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-863
vendor: Red Hat
product: libssh
affected:
  - libssh (all versions)
  - libssh-main (all versions)
  - libssh
  - libssh
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-22T18:14:50.808102Z'
published: '2026-07-21'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T23:09:45.220Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-59851'
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/security/cve/CVE-2026-59851'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2498184'
    label: RHBZ#2498184
tags:
  - cve.org
epss: 0.00489
epssPercentile: 0.42359
ingestedAt: '2026-11-05T21:36:00.672Z'
---

## Overview

A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.

## Affected

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

## Remediation

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

### Workarounds

Disable GSSAPIKeyExchange.