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.
Metrics
CVSS 3.1 6.8/10
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:NWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| — | — | >= 6.8p1, <= 9.9p1 |
| Red Hat | Red Hat Enterprise Linux 8 | — |
| Red Hat | Red Hat Enterprise Linux 8 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat Enterprise Linux 9 | — |
| Red Hat | Red Hat Enterprise Linux 9.4 Extended Update Support | — |
| Red Hat | Red Hat Discovery 1.14 | — |
| 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 | — |
| 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 1518-4 PN/DP MFP | >= V3.1.5, < * |
| Siemens | SIMATIC S7-1500 CPU 1518F-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, < * |
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-2025-26465Third Party Advisory
- https://access.redhat.com/solutions/7109879
- https://bugzilla.redhat.com/show_bug.cgi?id=2344780Issue Tracking, Third Party Advisory
- https://seclists.org/oss-sec/2025/q1/144Mailing 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-2025-26466Third Party Advisory
- https://bugzilla.suse.com/show_bug.cgi?id=1237040Issue Tracking
- https://ftp.openbsd.org/pub/OpenBSD/patches/7.6/common/008_ssh.patch.sigPatch
- https://lists.debian.org/debian-lts-announce/2025/02/msg00020.htmlThird Party Advisory
- https://lists.mindrot.org/pipermail/openssh-unix-announce/2025-February/000161.htmlThird Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2025-26465Third Party Advisory
- https://security.netapp.com/advisory/ntap-20250228-0003/Third Party Advisory
- https://ubuntu.com/security/CVE-2025-26465Third Party Advisory
- https://www.openssh.com/releasenotes.html#9.9p2Release Notes
- https://www.openwall.com/lists/oss-security/2025/02/18/1Mailing List, Third Party Advisory
- https://www.openwall.com/lists/oss-security/2025/02/18/4Mailing 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-opensshThird Party Advisory
- https://www.vicarius.io/vsociety/posts/cve-2025-26465-mitigate-vulnerable-opensshMitigation, Third Party Advisory
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-585531.html
- https://seclists.org/oss-sec/2025/q1/144Mailing List, Third Party Advisory
Timeline
- Published
- Feb 18, 2025
- Last modified
- Nov 5, 2026
- NVD status
- Modified