Linux Distros Unpatched Vulnerability : CVE-2026-59851

high Nessus Plugin ID 329661

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users. (CVE-2026-59851)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: High

ID: 329661

File Name: unpatched_CVE_2026_59851.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Misc.

Published: 7/25/2026

Updated: 7/25/2026

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 58.14

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.7

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

CVSS Score Source: CVE-2026-59851

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 8.1

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, cpe:/o:debian:debian_linux:14.0, cpe:/o:redhat:enterprise_linux:10, p-cpe:/a:canonical:ubuntu_linux:libssh, p-cpe:/a:debian:debian_linux:libssh, 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/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 7/21/2026

Reference Information

CVE: CVE-2026-59851

Detections

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