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

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.

Published: 2025-02-18 Last update: 2026-05-12 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-26465 is rated Moderate Risk (61.1/100): CVSS Medium severity, with high exploitation likelihood (EPSS 61.22%, 98th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-26465

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-09 61.74% 61.22% -0.52%
2 2026-06-06 64.52% 61.74% -2.78%
3 2026-06-02 — 64.52% —

Full EPSS history (78 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-26465

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 5.2 [email protected]
6.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 5.2 [email protected]

Weakness enumeration for CVE-2025-26465

OS Trackers for CVE-2025-26465

vendor priority summary link
alpine — CVE-2025-26465: 1 source package rows (openssh); 9 state rows across 6 repos (3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 2. https://security.alpinelinux.org/vuln/CVE-2025-26465
debian not yet assigned CVE-2025-26465 not yet assigned priority: Debian including 1 source packages (openssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-26465
gentoo normal CVE-2025-26465: 1 GLSA(s) (202502-01), 1 atom(s) (net-misc/openssh); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2025-26465
redhat medium — https://access.redhat.com/security/cve/CVE-2025-26465
suse medium CVE-2025-26465 severity moderate: SUSE including 349 source package names (15.7.20.5.1:openssh-9.6p1-150600.6.15.2, 15.7.20.5.1:openssh-clients-9.6p1-150600.6.15.2, …), 1692 product×package rows across 344 product lines (Container suse/git, Container suse/hpc/warewulf4-x86_64/sle-hpc-node, … (344 product lines)): Fixed 1471, Known Affected 221. https://www.suse.com/security/cve/CVE-2025-26465/
ubuntu medium CVE-2025-26465 medium priority: Ubuntu including 2 source packages (openssh, openssh-ssh1), 18 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 8, released 8, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2025-26465

Affected software / configurations for CVE-2025-26465

Vendor Product Version Raw CPE
openbsd openssh >= 6.9, <= 9.8 cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:*
openbsd openssh 6.8 cpe:2.3:a:openbsd:openssh:6.8:p1:*:*:*:*:*:*
openbsd openssh 9.9 cpe:2.3:a:openbsd:openssh:9.9:-:*:*:*:*:*:*
openbsd openssh 9.9 cpe:2.3:a:openbsd:openssh:9.9:p1:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp ontap 9 cpe:2.3:a:netapp:ontap:9:*:*:*:*:*:*:*
redhat openshift_container_platform 4.0 cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
debian debian_linux 12.0 cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

References for CVE-2025-26465

URL Tags
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 Third Party Advisory
https://access.redhat.com/solutions/7109879
https://bugzilla.redhat.com/show_bug.cgi?id=2344780 Issue Tracking Third Party Advisory
https://seclists.org/oss-sec/2025/q1/144 Mailing List Third 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-in-openssh-cve-2025-26465-cve-2025-26466 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 List Third Party Advisory
https://www.openwall.com/lists/oss-security/2025/02/18/4 Mailing List Third 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 Mitigation Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
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