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Amazon Linux 2 : openssh (ALAS-2025-2769)

medium Nessus Plugin ID 232352

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of openssh installed on the remote host is prior to 7.4p1-22. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2025-2769 advisory.

 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. (CVE-2025-26465)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update openssh' to update your system.

See Also

https://alas.aws.amazon.com/faqs.html

https://alas.aws.amazon.com/cve/html/CVE-2025-26465.html

https://alas.aws.amazon.com/AL2/ALAS-2025-2769.html

Plugin Details

Severity: Medium

ID: 232352

File Name: al2_ALAS-2025-2769.nasl

Version: 1.1

Type: local

Agent: unix

Published: 3/10/2025

Updated: 3/10/2025

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: High

Score: 8.5

CVSS v2

Risk Factor: High

Base Score: 7.1

Temporal Score: 5.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:N

CVSS Score Source: CVE-2025-26465

CVSS v3

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 6.1

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:openssh-clients, p-cpe:/a:amazon:linux:openssh-cavs, p-cpe:/a:amazon:linux:openssh-keycat, p-cpe:/a:amazon:linux:pam_ssh_agent_auth, p-cpe:/a:amazon:linux:openssh-askpass, p-cpe:/a:amazon:linux:openssh-server, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:openssh-ldap, p-cpe:/a:amazon:linux:openssh-server-sysvinit, p-cpe:/a:amazon:linux:openssh, p-cpe:/a:amazon:linux:openssh-debuginfo

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: No known exploits are available

Patch Publication Date: 2/26/2025

Vulnerability Publication Date: 2/11/2025

Reference Information

CVE: CVE-2025-26465

IAVA: 2025-A-0126