---
id: CVE-2025-26465
title: >-
  A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is
  enabled
summary: >-
  A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is
  enabled. A machine-in-the-middle attack can be performed by a malicious
  machine impersonating a legit server. This issue occurs due to how OpenSSH
  mishandles error …
severity: medium
cvss: 6.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N'
cwe:
  - CWE-390
vendor: openbsd
product: openssh
affected:
  - 'openssh >= 6.9, <= 9.8'
  - openssh = 6.8
  - openssh = 9.9
  - active_iq_unified_manager
  - ontap = 9
  - openshift_container_platform = 4.0
  - debian_linux = 11.0
  - debian_linux = 12.0
  - enterprise_linux = 9.0
published: '2025-02-18'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-26465'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2025:16823'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2025:3837'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2025:6993'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2025:8385'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2025-26465'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/solutions/7109879'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2344780'
    label: secalert@redhat.com
  - url: 'https://seclists.org/oss-sec/2025/q1/144'
    label: secalert@redhat.com
  - url: 'http://seclists.org/fulldisclosure/2025/Feb/18'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'http://seclists.org/fulldisclosure/2025/May/7'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'http://seclists.org/fulldisclosure/2025/May/8'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://blog.qualys.com/vulnerabilities-threat-research/2025/02/18/qualys-tru-discovers-two-vulnerabilities-in-openssh-cve-2025-26465-cve-2025-26466
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://bugzilla.suse.com/show_bug.cgi?id=1237040'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://ftp.openbsd.org/pub/OpenBSD/patches/7.6/common/008_ssh.patch.sig'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/02/msg00020.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.mindrot.org/pipermail/openssh-unix-announce/2025-February/000161.html
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security-tracker.debian.org/tracker/CVE-2025-26465'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20250228-0003/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://ubuntu.com/security/CVE-2025-26465'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openssh.com/releasenotes.html#9.9p2'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openwall.com/lists/oss-security/2025/02/18/1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.openwall.com/lists/oss-security/2025/02/18/4'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.theregister.com/2025/02/18/openssh_vulnerabilities_mitm_dos/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://www.vicarius.io/vsociety/posts/cve-2025-26465-detect-vulnerable-openssh
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://www.vicarius.io/vsociety/posts/cve-2025-26465-mitigate-vulnerable-openssh
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-585531.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://seclists.org/oss-sec/2025/q1/144'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - exploit-available
epss: 0.07723
epssPercentile: 0.94357
ingestedAt: '2026-07-14T13:36:55.021Z'
exploits:
  github: 2
  githubRepos:
    - 'https://github.com/rxerium/CVE-2025-26465'
    - 'https://github.com/dolutech/patch-manual-CVE-2025-26465-e-CVE-2025-26466'
  checkedAt: '2026-09-24T07:52:53.156Z'
exploitAvailable: true
---

## Overview

A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. A machine-in-the-middle attack can be performed by a malicious machine impersonating a legit server. This issue occurs due to how OpenSSH mishandles error codes in specific conditions when verifying the host key. For an attack to be considered successful, the attacker needs to manage to exhaust the client's memory resource first, turning the attack complexity high.

## Affected

- `openssh >= 6.9, <= 9.8`
- `openssh = 6.8`
- `openssh = 9.9`
- `active_iq_unified_manager`
- `ontap = 9`
- `openshift_container_platform = 4.0`
- `debian_linux = 11.0`
- `debian_linux = 12.0`
- `enterprise_linux = 9.0`

## Remediation

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