RHEL 10 : libssh (RHSA-2026:55855)

high Nessus Plugin ID 337346

Synopsis

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

Description

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:55855 advisory.

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

Security Fix(es):

* libssh: libssh: information disclosure via short GSSAPI Curve25519 public key (CVE-2026-59842)

* libssh: libssh: denial of service via zero advertised channel packet size (CVE-2026-59843)

* libssh: libssh: denial of service via oversized SFTP read length (CVE-2026-59844)

* libssh: libssh: denial of service via unchecked ProxyCommand fork() failure (CVE-2026-59845)

* libssh: libssh: information disclosure via ProxyCommand %r username expansion (CVE-2026-59846)

* libssh: libssh: integrity downgrade via OpenSSL AES-GCM tag verification (CVE-2026-59847)

* libssh: libssh: denial of service via SFTP responses with unknown request IDs (CVE-2026-59848)

* libssh: libssh: denial of service via automatic certificate authentication loop (CVE-2026-59849)

* libssh: libssh: use-after-free via data callbacks on closed channels (CVE-2026-59850)

* libssh: libssh: authentication bypass via missing GSSAPI principal check (CVE-2026-59851)

* libssh: libssh: stack buffer overflow in SFTP server longname construction (CVE-2026-15370)

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 libssh package based on the guidance in RHSA-2026:55855.

Plugin Details

Severity: High

ID: 337346

File Name: redhat-RHSA-2026-55855.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 8/18/2026

Updated: 8/18/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.17

Vendor

Vendor Severity: Important

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-2026-59847

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

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

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:10.2, p-cpe:/a:redhat:enterprise_linux:libssh-config, p-cpe:/a:redhat:enterprise_linux:libssh-devel, p-cpe:/a:redhat:enterprise_linux:libssh

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: 8/17/2026

Vulnerability Publication Date: 7/21/2026

Reference Information

CVE: CVE-2026-15370, CVE-2026-59842, CVE-2026-59843, CVE-2026-59844, CVE-2026-59845, CVE-2026-59846, CVE-2026-59847, CVE-2026-59848, CVE-2026-59849, CVE-2026-59850, CVE-2026-59851

CWE: 121, 125, 253, 390, 416, 770, 78, 789, 835, 863

RHSA: 2026:55855

Detections

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