RHEL 9 : openssh (RHSA-2026:76993)

critical Nessus Plugin ID 363763

Synopsis

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

Description

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:76993 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: Use-after-free vulnerability during host key re-exchange on the client side (CVE-2026-60002)

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

* openssh: OpenSSH: `scp` file misplacement vulnerability during remote copy (CVE-2026-59996)

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-2026:76993.

Plugin Details

Severity: Critical

ID: 363763

File Name: redhat-RHSA-2026-76993.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 10/7/2026

Updated: 10/7/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.5

Percentile: 57.6

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: High

Base Score: 9.7

Temporal Score: 7.6

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

CVSS Score Source: CVE-2026-60002

CVSS v3

Risk Factor: Critical

Base Score: 9.4

Temporal Score: 8.4

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

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

Vulnerability Information

CPE: cpe:/o:redhat:rhel_e4s:9.4, p-cpe:/a:redhat:enterprise_linux:openssh-clients, p-cpe:/a:redhat:enterprise_linux:openssh-server

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: 10/7/2026

Vulnerability Publication Date: 6/23/2026

Reference Information

CVE: CVE-2026-55653, CVE-2026-55655, CVE-2026-59995, CVE-2026-59996, CVE-2026-59999, CVE-2026-60002

CWE: 22, 358, 415, 825, 923

RHSA: 2026:76993

Detections

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