CVE-2025-26465

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.

• CWE-390

• 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://seclists.org/oss-sec/2025/q1/144Mailing List, Third Party Advisory

Published

Feb 18, 2025

Last Modified

Jun 17, 2026

Status

Modified