#VU104035 Man-in-the-Middle (MitM) attack in OpenSSH - CVE-2025-26465

Vulnerability identifier: #VU104035

Vulnerability risk: Medium

CVSSv4.0: 2.1 [CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2025-26465

CWE-ID: CWE-300

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
OpenSSH
Server applications / Remote management servers, RDP, SSH

Vendor: OpenSSH

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to incorrect processing of user-supplied data in ssh(1). A remote attacker can perform server impersonation when VerifyHostKeyDNS enabled.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

OpenSSH: 9.5p1 - 9.9p1

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External links
https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.