CVE-2025-26465
Openssh: machine-in-the-middle attack if verifyhostkeydns is enabled
At a glance
- Severity
- MEDIUM 6.8
- EPSS
- EPSS 7.72 % · percentile 95 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- redhat
- NVD status
- Modified
Description
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.
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 6.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N | redhat |
| CVSS 3.1 | MEDIUM 6.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N | NVD · secalert@redhat.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N | NVD · nvd@nist.gov (Primary) |
Weaknesses (CWE)
European references
- ENISA EUVD · EUVD-2025-4686
- GCVE · GCVE-0-2025-26465
CERT-FR advisories
- CERTFR-2025-AVI-0969 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0492 — Multiples vulnérabilités dans les produits Siemens · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0486 — Multiples vulnérabilités dans les produits Qnap · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0393 — Multiples vulnérabilités dans les produits Apple · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0139 — Multiples vulnérabilités dans OpenSSH · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:*≥ 6.9 ≤ 9.8cpe:2.3:a:openbsd:openssh:6.8:p1:*:*:*:*:*:*cpe:2.3:a:openbsd:openssh:9.9:-:*:*:*:*:*:*cpe:2.3:a:openbsd:openssh:9.9:p1:*:*:*:*:*:*cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*cpe:2.3:a:netapp:ontap:9:*:*:*:*:*:*:*cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
Affected products
| Product | Versions |
|---|---|
| OpenSSH | affected 6.8p1 ≤ 9.9p1 |
| Red Hat · Red Hat Enterprise Linux 8 | unaffected 0:8.0p1-26.el8_10 < * |
| Red Hat · Red Hat Enterprise Linux 8 | unaffected 0:8.0p1-26.el8_10 < * |
| Red Hat · Red Hat Enterprise Linux 9 | unaffected 0:8.7p1-45.el9 < * |
| Red Hat · Red Hat Enterprise Linux 9 | unaffected 0:8.7p1-45.el9 < * |
| Red Hat · Red Hat Enterprise Linux 9.4 Extended Update Support | unaffected 0:8.7p1-38.el9_4.5 < * |
| Red Hat · Red Hat Discovery 1.14 | unaffected 1.14.3-1748529279 < * |
| Red Hat · Red Hat Enterprise Linux 10 | |
| Red Hat · Red Hat Enterprise Linux 6 | |
| Red Hat · Red Hat Enterprise Linux 7 | |
| Red Hat · Red Hat OpenShift Container Platform 4 |
References
- https://access.redhat.com/errata/RHSA-2025:16823
- https://access.redhat.com/errata/RHSA-2025:3837
- https://access.redhat.com/errata/RHSA-2025:6993
- https://access.redhat.com/errata/RHSA-2025:8385
- https://access.redhat.com/security/cve/CVE-2025-26465
- https://access.redhat.com/solutions/7109879
- https://bugzilla.redhat.com/show_bug.cgi?id=2344780
- https://seclists.org/oss-sec/2025/q1/144
- https://lists.debian.org/debian-lts-announce/2025/02/msg00020.html
- https://www.openwall.com/lists/oss-security/2025/02/18/1
- https://www.openwall.com/lists/oss-security/2025/02/18/4
- https://www.theregister.com/2025/02/18/openssh_vulnerabilities_mitm_dos/
- https://bugzilla.suse.com/show_bug.cgi?id=1237040
- https://security-tracker.debian.org/tracker/CVE-2025-26465
- https://ftp.openbsd.org/pub/OpenBSD/patches/7.6/common/008_ssh.patch.sig
- https://ubuntu.com/security/CVE-2025-26465
- https://www.openssh.com/releasenotes.html#9.9p2
- https://blog.qualys.com/vulnerabilities-threat-research/2025/02/18/qualys-tru-discovers-two-vulnerabilities-in-openssh-cve-2025-26465-cve-2025-26466
- https://lists.mindrot.org/pipermail/openssh-unix-announce/2025-February/000161.html
- https://security.netapp.com/advisory/ntap-20250228-0003/
- https://www.vicarius.io/vsociety/posts/cve-2025-26465-detect-vulnerable-openssh
- https://www.vicarius.io/vsociety/posts/cve-2025-26465-mitigate-vulnerable-openssh
- http://seclists.org/fulldisclosure/2025/May/8
- http://seclists.org/fulldisclosure/2025/May/7
- http://seclists.org/fulldisclosure/2025/Feb/18
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-585531.html
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |