Amazon Linux 2023 : openssh, openssh-clients, openssh-keycat (ALAS2023-2026-3354)

high Nessus Plugin ID 374367

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-3354 advisory.

In sftp in OpenSSH before 10.6, a server can trigger directory traversal (causing files to be written to unintended locations) during a recursive copy operation. (CVE-2026-106552)

In sshd in OpenSSH before 10.6, credentials can incorrectly persist after failure of a GSSAPIAuthentication authentication attempt. (CVE-2026-106553)

In sshd in OpenSSH before 10.6, GSSAPIAuthentication authentication state can incorrectly be persisted across authentication attempts. (CVE-2026-106555)

In sshd and ssh in OpenSSH before 10.6, an LZ77 dictionary coder can be used even though this is contraindicated by the arXiv 2609.07709 Crossing the Streams findings. (CVE-2026-106582)

In ssh in OpenSSH before 10.6, a $ or \ character can occur in a command-line username, leading to injection. (CVE-2026-106583)

In ssh-keygen in OpenSSH before 10.6, certificates could have incorrect expiration times because of Daylight Saving mishandling. There can be a slightly more severe effect on users in certain Antarctic locations. (CVE-2026-106584)

In sshd and ssh in OpenSSH before 10.6, there is no check for whether the maximum packet length is exceeded during decompression of highly compressed data. (CVE-2026-106585)

In sshd in OpenSSH before 10.6, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not, a different vulnerability than CVE-2026-73283. (CVE-2026-106586)

In sshd in OpenSSH before 10.6, the value none for a configuration option is sometimes interpreted as a filename but was intended to mean that a feature is disabled. (CVE-2026-106587)

sftp in OpenSSH before 10.4 does not properly constrain the location of downloaded files when sftp server:/path . is used with an attacker-controlled server. (CVE-2026-59995)

internal-sftp in sshd in OpenSSH before 10.4 recognizes only the first 9 command-line arguments, which can be important if a later command-line argument would have helped to ensure the intended security properties of an SFTP connection. (CVE-2026-59997)

sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no value if the server is in Windows Active Directory. (CVE-2026-59998)

In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over PermitTunnel=yes, but did not. (CVE-2026-59999)

sshd in OpenSSH before 10.4 allows remote attackers to cause a denial of service (resource consumption from excessive authentication attempts) because MaxAuthTries was mishandled for GSSAPIAuthentication.
(CVE-2026-60000)

sshd in OpenSSH before 10.4 does not always honor the minimum authentication delay. (CVE-2026-60001)

In ssh-agent in OpenSSH before 10.5, some operations can occur remotely but were intended to occur only locally, including operations that add tokens or use keys. This is caused by misinteraction between agent locking and the [email protected] extension. (CVE-2026-73281)

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote- forwarding operations are concurrent. (CVE-2026-73282)

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not. (CVE-2026-73283)

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

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

Solution

Run 'dnf update openssh --releasever 2023.12.20261102' or or 'dnf update --advisory ALAS2023-2026-3354 --releasever 2023.12.20261102' to update your system.

Plugin Details

Severity: High

ID: 374367

File Name: al2023_ALAS2023-2026-3354.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 10/30/2026

Updated: 10/30/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 92.99

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2026-59999

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

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

CVSS Score Source: CVE-2026-106583

Vulnerability Information

CPE: cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:openssh-clients-debuginfo, p-cpe:/a:amazon:linux:openssh-clients, p-cpe:/a:amazon:linux:openssh-debuginfo, p-cpe:/a:amazon:linux:openssh-debugsource, p-cpe:/a:amazon:linux:openssh-keycat-debuginfo, p-cpe:/a:amazon:linux:openssh-keycat, p-cpe:/a:amazon:linux:openssh-server-debuginfo, p-cpe:/a:amazon:linux:openssh-server, p-cpe:/a:amazon:linux:openssh-sk-dummy-debuginfo, p-cpe:/a:amazon:linux:openssh-sk-dummy, p-cpe:/a:amazon:linux:openssh, p-cpe:/a:amazon:linux:pam_ssh_agent_auth-debuginfo, p-cpe:/a:amazon:linux:pam_ssh_agent_auth

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

Exploit Ease: No known exploits are available

Patch Publication Date: 10/30/2026

Vulnerability Publication Date: 7/8/2026

Reference Information

CVE: CVE-2026-106552, CVE-2026-106553, CVE-2026-106555, CVE-2026-106582, CVE-2026-106583, CVE-2026-106584, CVE-2026-106585, CVE-2026-106586, CVE-2026-106587, CVE-2026-59995, CVE-2026-59997, CVE-2026-59998, CVE-2026-59999, CVE-2026-60000, CVE-2026-60001, CVE-2026-73281, CVE-2026-73282, CVE-2026-73283

IAVA: 2026-A-0691-S, 2026-A-0847-S, 2026-A-1103

Detections

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