RHEL 8 : openssh (RHSA-2026:99573)

high Nessus Plugin ID 379611

Synopsis

The remote Red Hat host is missing one or more security updates for openssh.

Description

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:99573 advisory.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

* openssh: Local MITM of X11 forwarding via abstract UNIX socket pre-binding in Red Hat Enterprise Linux OpenSSH client versions (CVE-2026-55655)

* openssh: Double free in Red Hat Enterprise Linux versions of OpenSSH DH-GEX client path during FIPS known-group validation leads to client-side denial of service (CVE-2026-55653)

* openssh: OpenSSH: sftp client allows attacker to control downloaded file location (CVE-2026-59995)

* openssh: OpenSSH sshd: Security bypass due to incorrect handling of forwarding and tunneling options (CVE-2026-59999)

* openssh: openssh: Information disclosure via shared compression side-channel (CVE-2026-106582)

* openssh: OpenSSH: Credential disclosure via failed GSSAPI authentication (CVE-2026-106553)

* openssh: openssh: Denial of service via oversized decompressed packets (CVE-2026-106585)

* openssh: openssh: Command injection via unvalidated command-line username (CVE-2026-106583)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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

Update the RHEL openssh package based on the guidance in RHSA-2026:99573.

Plugin Details

Severity: High

ID: 379611

File Name: redhat-RHSA-2026-99573.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 11/12/2026

Updated: 11/12/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 92.79

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.1

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: 7

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:P/RL:O/RC:C

CVSS Score Source: CVE-2026-106583

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:8, cpe:/o:redhat:rhel_aus:8.4, p-cpe:/a:redhat:enterprise_linux:openssh-askpass, p-cpe:/a:redhat:enterprise_linux:openssh-cavs, p-cpe:/a:redhat:enterprise_linux:openssh-clients, p-cpe:/a:redhat:enterprise_linux:openssh-keycat, p-cpe:/a:redhat:enterprise_linux:openssh-ldap, p-cpe:/a:redhat:enterprise_linux:openssh-server, p-cpe:/a:redhat:enterprise_linux:openssh, p-cpe:/a:redhat:enterprise_linux:pam_ssh_agent_auth

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 11/12/2026

Vulnerability Publication Date: 6/23/2026

Reference Information

CVE: CVE-2026-106553, CVE-2026-106582, CVE-2026-106583, CVE-2026-106585, CVE-2026-55653, CVE-2026-55655, CVE-2026-59995, CVE-2026-59999

CWE: 205, 22, 358, 409, 415, 459, 78, 923

RHSA: 2026:99573

Detections

Analytics