Bug 2451106 (CVE-2026-33999)

Summary:	CVE-2026-33999 xorg: xwayland: X.Org X server: Denial of Service via integer underflow in XKB compatibility map handling
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	rhel-process-autobot, security-response-team, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	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.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2476954, 2476956, 2476957
Bug Blocks:

Description OSIDB Bzimport 2026-03-25 06:29:42 UTC

Integer Underflow (Wraparound) vulnerability in the XKB compatibility map handling of the X.Org X server. The issue occurs in XkbSetCompatMap() when a previously truncated “compat” buffer leaves unused space that is later reused without correctly updating the count of valid entries. This can cause internal size/index calculations to become inconsistent and potentially underflow, resulting in a buffer read overrun when subsequent XKB requests are processed. An attacker with access to the X11 server (local or via remote X11 forwarding/SSH tunneling) can trigger the flaw without user interaction, leading to memory-safety violations and potentially a crash or more severe impact depending on how Xorg/Xwayland is deployed.

Comment 4 errata-xmlrpc 2026-04-27 08:29:51 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:10739 https://access.redhat.com/errata/RHSA-2026:10739

Comment 5 errata-xmlrpc 2026-04-28 11:20:59 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:11352 https://access.redhat.com/errata/RHSA-2026:11352

Comment 6 errata-xmlrpc 2026-04-28 14:53:16 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:11369 https://access.redhat.com/errata/RHSA-2026:11369

Comment 7 errata-xmlrpc 2026-04-28 17:58:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:11388 https://access.redhat.com/errata/RHSA-2026:11388

Comment 8 errata-xmlrpc 2026-04-29 12:01:21 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:11656 https://access.redhat.com/errata/RHSA-2026:11656

Comment 9 errata-xmlrpc 2026-04-29 13:07:51 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:11692 https://access.redhat.com/errata/RHSA-2026:11692

Comment 10 errata-xmlrpc 2026-05-04 12:29:09 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:13414 https://access.redhat.com/errata/RHSA-2026:13414