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.

Project Subscriptions

Vendors Products
Enterprise Linux Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

To mitigate this issue, restrict access to the X11 server. For remote access, disable X11 forwarding in SSH configurations if not required. Edit `/etc/ssh/sshd_config` and set `X11Forwarding no`. After modifying the configuration, restart the `sshd` service using `systemctl restart sshd`. Disabling X11 forwarding may impact remote graphical applications.

History

Fri, 24 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Fri, 24 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Thu, 23 Apr 2026 15:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Xorg: xwayland: x.org x server: denial of service via integer underflow in xkb compatibility map handling
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-191
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-04-24T13:37:08.875Z

Reserved: 2026-03-25T04:53:13.614Z

Link: CVE-2026-33999

cve-icon Vulnrichment

Updated: 2026-04-24T13:37:04.491Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-23T16:16:24.623

Modified: 2026-04-24T14:41:55.890

Link: CVE-2026-33999

cve-icon Redhat

Severity : Important

Publid Date: 2026-04-23T14:11:12Z

Links: CVE-2026-33999 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses