RHEL 9 : libssh (RHSA-2026:18683)

high Nessus Plugin ID 315440

Synopsis

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

Description

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:18683 advisory.

libssh is a library which implements the SSH protocol. It can be used to implement client and server applications.

Security Fix(es):

* libssh: Double Free Vulnerability in libssh Key Export Functions (CVE-2025-5351)

* libssh: Use of uninitialized variable in privatekey_from_file() (CVE-2025-4878)

* libssh: Write beyond bounds in binary to base64 conversion functions (CVE-2025-4877)

* libssh: NULL Pointer Dereference in libssh KEX Session ID Calculation (CVE-2025-8114)

* libssh: Memory Exhaustion via Repeated Key Exchange in libssh (CVE-2025-8277)

* libssh: Buffer underflow in ssh_get_hexa() on invalid input (CVE-2026-0966)

* libssh: Improper sanitation of paths received from SCP servers (CVE-2026-0964)

* libssh: libssh: Denial of Service via improper configuration file handling (CVE-2026-0965)

* libssh: libssh: Denial of Service via inefficient regular expression processing (CVE-2026-0967)

* libssh: libssh: Denial of Service due to malformed SFTP message (CVE-2026-0968)

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.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 9 Release Notes linked from 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 libssh package based on the guidance in RHSA-2026:18683.

Plugin Details

Severity: High

ID: 315440

File Name: redhat-RHSA-2026-18683.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 5/19/2026

Updated: 5/19/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.0

Vendor

Vendor Severity: Moderate

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 6.3

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

CVSS Score Source: CVE-2026-0966

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

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

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

Vulnerability Information

CPE: p-cpe:/a:redhat:enterprise_linux:libssh, p-cpe:/a:redhat:enterprise_linux:libssh-devel, p-cpe:/a:redhat:enterprise_linux:libssh-config, cpe:/o:redhat:enterprise_linux:9

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

Exploit Ease: No known exploits are available

Patch Publication Date: 5/19/2026

Vulnerability Publication Date: 7/3/2025

Reference Information

CVE: CVE-2025-4877, CVE-2025-4878, CVE-2025-5351, CVE-2025-8114, CVE-2025-8277, CVE-2026-0964, CVE-2026-0965, CVE-2026-0966, CVE-2026-0967, CVE-2026-0968

CWE: 124, 1333, 22, 401, 415, 416, 476, 73, 787

RHSA: 2026:18683

Detections

Analytics