CVE-2025-26465

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.

References

https://www.securityweek.com/openssh-patches-vulnerabilities-allowing-mitm-dos-attacks/

https://www.bleepingcomputer.com/news/security/new-openssh-flaws-expose-ssh-servers-to-mitm-and-dos-attacks/

https://thehackernews.com/2025/02/new-openssh-flaws-enable-man-in-middle.html

https://www.theregister.com/2025/02/18/openssh_vulnerabilities_mitm_dos/

https://www.openwall.com/lists/oss-security/2025/02/18/4

https://www.openwall.com/lists/oss-security/2025/02/18/1

https://www.openssh.com/releasenotes.html#9.9p2

https://ubuntu.com/security/CVE-2025-26465

https://security-tracker.debian.org/tracker/CVE-2025-26465

https://seclists.org/oss-sec/2025/q1/144

https://lists.mindrot.org/pipermail/openssh-unix-announce/2025-February/000161.html

https://lists.debian.org/debian-lts-announce/2025/02/msg00020.html

https://ftp.openbsd.org/pub/OpenBSD/patches/7.6/common/008_ssh.patch.sig

https://bugzilla.suse.com/show_bug.cgi?id=1237040

https://bugzilla.redhat.com/show_bug.cgi?id=2344780

https://access.redhat.com/security/cve/CVE-2025-26465

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3