6.8Medium

CVE-2025-26465Openssh: machine-in-the-middle attack if verifyhostkeydns is enabled

OpenSSH; Red Hat Red Hat Enterprise Linux 8; Red Hat Red Hat Enterprise Linux 9; Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support Published: 2025-02-18 21:27 (1 year ago)

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.

Weakness (CWE): CWE-390

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

Vendor	Product	Versions
debian	debian linux	11.0
discovery	1.14	—
enterprise linux	8	—
enterprise linux	9	—
netapp	active iq unified manager	—
netapp	ontap	9
openbsd	openssh	6.9 – ≤ 9.8
redhat	enterprise linux	9.0
redhat	openshift container platform	4.0
Red Hat	Red Hat Discovery 1.14	all versions
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 Enterprise Linux 8	all versions
Red Hat	Red Hat Enterprise Linux 9	all versions
Red Hat	Red Hat Enterprise Linux 9.4 Extended Update Support	all versions
Red Hat	Red Hat OpenShift Container Platform 4	all versions
rhel eus	9.4	—
Siemens	SIDIS Secured SmartPlug	< V7.26.0310
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	V3.1.5
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	V3.1.5
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	V3.1.5
—	OpenSSH	6.8p1 – ≤ 9.9p1

References and patches

RHSA-2025:16823 vendor-advisory
RHSA-2025:3837 vendor-advisory
RHSA-2025:6993 vendor-advisory
RHSA-2025:8385 vendor-advisory
https://access.redhat.com/security/cve/CVE-2025-26465 vdb-entryThird Party Advisory
https://access.redhat.com/solutions/7109879
RHBZ#2344780 issue-trackingIssue TrackingThird Party Advisory
https://seclists.org/oss-sec/2025/q1/144 Mailing ListThird Party Advisory
http://seclists.org/fulldisclosure/2025/Feb/18
http://seclists.org/fulldisclosure/2025/May/7
http://seclists.org/fulldisclosure/2025/May/8
https://blog.qualys.com/vulnerabilities-threat-research/2025/02/18/qualys-tru-discovers-two-vulnerabilities-i… Third Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1237040 Issue Tracking
https://ftp.openbsd.org/pub/OpenBSD/patches/7.6/common/008_ssh.patch.sig Patch
https://lists.debian.org/debian-lts-announce/2025/02/msg00020.html Third Party Advisory
https://lists.mindrot.org/pipermail/openssh-unix-announce/2025-February/000161.html Third Party Advisory
https://security-tracker.debian.org/tracker/CVE-2025-26465 Third Party Advisory
https://security.netapp.com/advisory/ntap-20250228-0003/ Third Party Advisory
https://ubuntu.com/security/CVE-2025-26465 Third Party Advisory
https://www.openssh.com/releasenotes.html#9.9p2 Release Notes
https://www.openwall.com/lists/oss-security/2025/02/18/1 Mailing ListThird Party Advisory
https://www.openwall.com/lists/oss-security/2025/02/18/4 Mailing ListThird Party Advisory
https://www.theregister.com/2025/02/18/openssh_vulnerabilities_mitm_dos/ Press/Media Coverage
https://www.vicarius.io/vsociety/posts/cve-2025-26465-detect-vulnerable-openssh Third Party Advisory
https://www.vicarius.io/vsociety/posts/cve-2025-26465-mitigate-vulnerable-openssh MitigationThird Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
https://cert-portal.siemens.com/productcert/html/ssa-585531.html

CPE matches (NVD) (10)

cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:* ≥ 6.9 ≤ 9.8
cpe: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:*:*:*:*:*:*:*

CVSS score

6.8Medium

Source: redhat · CVSS 3.1

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

All scores (3)

cna	CVSS 3.1	6.8Medium
secalert@redhat.com	CVSS 3.1	6.8Medium
nvd	CVSS 3.1	6.8Medium

EPSS (chance of exploitation in 30 days)

7.72%

higher than 95% of all CVEs

CISA assessment (SSVC)

Exploitation: poc
Automatable: no
Technical impact: total

Timeline

ID reserved2025-02-10
Published2025-02-18 21:27
Reached IP-DB2026-10-25 00:00
Last updated2026-11-05 19:17

Assigned by (CNA): redhat
NVD status: Modified

View at source: CVE.org · NVD

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