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Linux Distros Unpatched Vulnerability : CVE-2026-33999

high Nessus Plugin ID 306416

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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 the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts. (CVE-2026-33999)

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

Solution

There is no known solution at this time.

See Also

https://access.redhat.com/security/cve/cve-2026-33999

https://security-tracker.debian.org/tracker/CVE-2026-33999

https://ubuntu.com/security/CVE-2026-33999

Plugin Details

Severity: High

ID: 306416

File Name: unpatched_CVE_2026_33999.nasl

Version: 1.10

Type: Local

Agent: unix

Family: Misc.

Published: 4/14/2026

Updated: 5/4/2026

Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Low

Base Score: 2.1

Temporal Score: 1.8

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

CVSS Score Source: CVE-2026-33999

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 7.1

Vector: CVSS:3.0/AV:L/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: p-cpe:/a:canonical:ubuntu_linux:xorg-server, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-common, p-cpe:/a:redhat:enterprise_linux:tigervnc-server-applet, cpe:/o:debian:debian_linux:12.0, p-cpe:/a:centos:centos:tigervnc-license, p-cpe:/a:canonical:ubuntu_linux:xorg-server-hwe-16.04, cpe:/o:canonical:ubuntu_linux:25.10, p-cpe:/a:centos:centos:xorg-x11-server-xvfb, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xnest, p-cpe:/a:canonical:ubuntu_linux:xorg-server-hwe-18.04, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-source, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:redhat:enterprise_linux:tigervnc-license, p-cpe:/a:redhat:enterprise_linux:tigervnc-server, p-cpe:/a:centos:centos:xorg-x11-server-source, cpe:/o:debian:debian_linux:13.0, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xephyr, cpe:/o:canonical:ubuntu_linux:14.04:-:lts, p-cpe:/a:redhat:enterprise_linux:tigervnc, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xorg, p-cpe:/a:canonical:ubuntu_linux:xwayland, p-cpe:/a:centos:centos:xorg-x11-server-devel, p-cpe:/a:redhat:enterprise_linux:tigervnc-server-module, p-cpe:/a:debian:debian_linux:xwayland, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xdmx, p-cpe:/a:centos:centos:xorg-x11-server, p-cpe:/a:redhat:enterprise_linux:tigervnc-icons, p-cpe:/a:centos:centos:tigervnc, p-cpe:/a:centos:centos:tigervnc-server, cpe:/o:centos:centos:7, p-cpe:/a:centos:centos:xorg-x11-server-xdmx, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:redhat:enterprise_linux:7, cpe:/o:canonical:ubuntu_linux:26.04, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server, p-cpe:/a:centos:centos:xorg-x11-server-xephyr, p-cpe:/a:debian:debian_linux:xorg-server, p-cpe:/a:redhat:enterprise_linux:tigervnc-server-minimal, p-cpe:/a:centos:centos:xorg-x11-server-xnest, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:centos:centos:tigervnc-server-module, p-cpe:/a:centos:centos:xorg-x11-server-xwayland, p-cpe:/a:centos:centos:tigervnc-server-minimal, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xvfb, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xwayland, cpe:/o:debian:debian_linux:11.0, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-devel, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:centos:centos:tigervnc-icons, p-cpe:/a:centos:centos:tigervnc-server-applet, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:centos:centos:xorg-x11-server-common, p-cpe:/a:centos:centos:xorg-x11-server-xorg, cpe:/o:redhat:enterprise_linux:6

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

Exploit Ease: No known exploits are available

Reference Information

CVE: CVE-2026-33999