What’s Vulnerable › Vulnerabilities
CVE-2025-26465: Openssh: machine-in-the-middle attack if verifyhostkeydns is enabled
- Severity: medium (CVSS 6.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 7.7% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2025-02-18 · updated 2026-10-21
- Weakness: CWE-390
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.
Affected products
- Debian Linux: 11.0, 12.0
- Active IQ Unified Manager for VMware vSphere, Linux, and Microsoft Windows: all versions
- NetApp ONTAP 9: 9
- OpenSSH: from 6.9 through 9.8; 6.8-p1, 9.9, 9.9-p1
- Red Hat Enterprise Linux: 9.0
- Red Hat OpenShift Container Platform 4.18: 4.0
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
- 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
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