Bug 2485384 (CVE-2026-50259)

Summary:	CVE-2026-50259 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB SetMap request via mapWidths indexing
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, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.	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:

Description OSIDB Bzimport 2026-06-05 08:11:53 UTC

_XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow.

Any X client that can connect to the server can trigger this issue. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Components affected: xorg-x11-server, xorg-x11-server-Xwayland
Versions affected: xorg-x11-server <= 21.1.22, xorg-x11-server-Xwayland <= 24.1.9

Fixed upstream in xorg-server-21.1.23 and xwayland-24.1.12.
Fix: https://gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b

Reported via ZDI-CAN-30161 (Trend Micro Zero Day Initiative). Tracking: PSIRTSUPT-16950.

Comment 1 errata-xmlrpc 2026-06-17 12:06:39 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:26562 https://access.redhat.com/errata/RHSA-2026:26562

Comment 2 errata-xmlrpc 2026-06-17 14:49:33 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:26590 https://access.redhat.com/errata/RHSA-2026:26590

Comment 3 errata-xmlrpc 2026-06-17 15:41:10 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:26610 https://access.redhat.com/errata/RHSA-2026:26610

Comment 4 errata-xmlrpc 2026-06-17 17:49:10 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:26709 https://access.redhat.com/errata/RHSA-2026:26709

Comment 5 errata-xmlrpc 2026-06-22 02:25:16 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:26566 https://access.redhat.com/errata/RHSA-2026:26566

Comment 6 errata-xmlrpc 2026-06-24 10:22:48 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:28923 https://access.redhat.com/errata/RHSA-2026:28923

Comment 7 errata-xmlrpc 2026-06-25 12:55:43 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:29844 https://access.redhat.com/errata/RHSA-2026:29844

Comment 8 errata-xmlrpc 2026-07-07 05:59:15 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7 Extended Lifecycle Support

Via RHSA-2026:36083 https://access.redhat.com/errata/RHSA-2026:36083

Comment 9 errata-xmlrpc 2026-07-07 06:09:08 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:36086 https://access.redhat.com/errata/RHSA-2026:36086

Comment 10 errata-xmlrpc 2026-07-07 06:19:11 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:36087 https://access.redhat.com/errata/RHSA-2026:36087

Comment 11 errata-xmlrpc 2026-07-07 06:33:48 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:36085 https://access.redhat.com/errata/RHSA-2026:36085

Comment 12 errata-xmlrpc 2026-07-08 09:12:06 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:36633 https://access.redhat.com/errata/RHSA-2026:36633

Comment 13 errata-xmlrpc 2026-07-08 09:22:47 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:36632 https://access.redhat.com/errata/RHSA-2026:36632

Comment 14 errata-xmlrpc 2026-07-08 09:33:44 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:36634 https://access.redhat.com/errata/RHSA-2026:36634

Comment 15 errata-xmlrpc 2026-07-08 14:32:56 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:36768 https://access.redhat.com/errata/RHSA-2026:36768

Comment 16 errata-xmlrpc 2026-07-08 16:11:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

Via RHSA-2026:36791 https://access.redhat.com/errata/RHSA-2026:36791

Comment 17 errata-xmlrpc 2026-07-08 16:19:42 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:36792 https://access.redhat.com/errata/RHSA-2026:36792

Comment 18 errata-xmlrpc 2026-07-08 16:21:54 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:36798 https://access.redhat.com/errata/RHSA-2026:36798

Comment 19 errata-xmlrpc 2026-07-13 03:22:54 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:38502 https://access.redhat.com/errata/RHSA-2026:38502

Comment 20 errata-xmlrpc 2026-07-13 09:28:23 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

Via RHSA-2026:38810 https://access.redhat.com/errata/RHSA-2026:38810