Linux Distros Unpatched Vulnerability : CVE-2026-55200

critical Nessus Plugin ID 321726

Language:

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.

- libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution. (CVE-2026-55200)

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: Critical

ID: 321726

File Name: unpatched_CVE_2026_55200.nasl

Version: 1.7

Type: Local

Agent: unix

Family: Misc.

Published: 6/20/2026

Updated: 7/29/2026

Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.5

Percentile: 98.39

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 6.1

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

CVSS Score Source: CVE-2026-55200

CVSS v3

Risk Factor: High

Base Score: 8.3

Temporal Score: 7.9

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

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

CVSS v4

Risk Factor: Critical

Base Score: 9.2

Threat Score: 7.2

Threat Vector: CVSS:4.0/E:P

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:25.10, cpe:/o:centos:centos:7, cpe:/o:debian:debian_linux:11.0, cpe:/o:debian:debian_linux:12.0, cpe:/o:redhat:enterprise_linux:7, p-cpe:/a:canonical:ubuntu_linux:libssh2, p-cpe:/a:centos:centos:libssh2-devel, p-cpe:/a:centos:centos:libssh2-docs, p-cpe:/a:centos:centos:libssh2, p-cpe:/a:debian:debian_linux:libssh2, p-cpe:/a:redhat:enterprise_linux:libssh2-devel, p-cpe:/a:redhat:enterprise_linux:libssh2-docs, p-cpe:/a:redhat:enterprise_linux:libssh2

Required KB Items: Host/cpu, Host/local_checks_enabled, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 6/17/2026

Reference Information

CVE: CVE-2026-55200

Detections

Analytics