RHEL 9 : xorg-x11-server (RHSA-2026:20555)

critical Nessus Plugin ID 316884

Synopsis

The remote Red Hat host is missing one or more security updates for xorg-x11-server.

Description

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:20555 advisory.

X.Org is an open-source implementation of the X Window System. It provides the basic low-level functionality that full-fledged graphical user interfaces are designed upon.

Security Fix(es):

* xorg: xwayland: X.Org X server: Denial of Service via integer underflow in XKB compatibility map handling (CVE-2026-33999)

* xwayland: xorg: X.Org X server: Information disclosure and denial of service via out-of-bounds read in XKB geometry processing. (CVE-2026-34000)

* xorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption (CVE-2026-34001)

* xorg: xwayland: X.Org X server: Information disclosure or Denial of Service via out-of-bounds read in XKB modifier map handling (CVE-2026-34002)

* xorg: xwayland: X.Org X server: Information exposure and denial of service via out-of-bounds memory access (CVE-2026-34003)

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 xorg-x11-server package based on the guidance in RHSA-2026:20555.

Plugin Details

Severity: Critical

ID: 316884

File Name: redhat-RHSA-2026-20555.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 5/27/2026

Updated: 5/27/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7

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

CVSS Score Source: CVE-2026-34002

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

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

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

Vulnerability Information

CPE: p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xorg, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-devel, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xnest, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-source, cpe:/o:redhat:rhel_eus:9.4, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xdmx, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-common, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xvfb, p-cpe:/a:redhat:enterprise_linux:xorg-x11-server-xephyr

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: 5/26/2026

Vulnerability Publication Date: 4/14/2026

Reference Information

CVE: CVE-2026-33999, CVE-2026-34000, CVE-2026-34001, CVE-2026-34002, CVE-2026-34003

CWE: 125, 191, 805, 825

RHSA: 2026:20555

Detections

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