---
id: CVE-2026-55653
title: A flaw was found in OpenSSH
summary: >-
  A flaw was found in OpenSSH. A malicious SSH server can exploit a double free
  vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This
  occurs during FIPS (Federal Information Processing Standards) mode known-group
  va…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L'
cwe:
  - CWE-415
vendor: openbsd
product: openssh
affected:
  - openssh
  - hardened_images
  - openshift_container_platform = 4.0
  - enterprise_linux = 6.0
  - enterprise_linux = 7.0
  - enterprise_linux = 8.0
  - enterprise_linux = 9.0
  - enterprise_linux = 10.0
published: '2026-06-23'
updated: '2026-08-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55653'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:36759'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:47755'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:47756'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:47757'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:54387'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-55653'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2462351'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00296
epssPercentile: 0.22544
ingestedAt: '2026-08-24T13:03:31.720Z'
---

## Overview

A flaw was found in OpenSSH. A malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX group parameters. Successful exploitation leads to client-side process termination, resulting in a Denial of Service (DoS).

## Affected

- `openssh`
- `hardened_images`
- `openshift_container_platform = 4.0`
- `enterprise_linux = 6.0`
- `enterprise_linux = 7.0`
- `enterprise_linux = 8.0`
- `enterprise_linux = 9.0`
- `enterprise_linux = 10.0`

## Remediation

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