Multiple vulnerabilities in OpenBSD sshd and ssh client

Published: 2025-02-18 | Updated: 2025-02-21

Risk	Medium
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2025-26466 CVE-2025-26465
CWE-ID	CWE-20 CWE-300
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #1 is available.
Vulnerable software	OpenBSD Operating systems & Components / Operating system
Vendor	OpenBSD

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Input validation error

EUVDB-ID: #VU104034

Risk: Medium

CVSSv4.0: 7.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2025-26466

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input related to SSH2_MSG_PING handling in sshd(8). A remote attacker can send specially crafted packets to the server and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

OpenBSD: 7.5 - 7.6

CPE2.3

External links

https://www.openbsd.org/errata76.html#008
https://www.openbsd.org/errata75.html#017

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. However, proof of concept for this vulnerability is available.

2) Man-in-the-Middle (MitM) attack

EUVDB-ID: #VU104035

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 - Channel Accessible by Non-Endpoint ('Man-in-the-Middle')

Exploit availability: No