Bug 2485386 (CVE-2026-50261) - CVE-2026-50261 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in SyncChangeCounter()
Summary: CVE-2026-50261 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: us...
Keywords:
Status: NEW
Alias: CVE-2026-50261
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-06-05 08:12 UTC by OSIDB Bzimport
Modified: 2026-07-13 09:28 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:26562 0 None None None 2026-06-17 12:06:40 UTC
Red Hat Product Errata RHSA-2026:26566 0 None None None 2026-06-22 02:25:20 UTC
Red Hat Product Errata RHSA-2026:26590 0 None None None 2026-06-17 14:49:35 UTC
Red Hat Product Errata RHSA-2026:26610 0 None None None 2026-06-17 15:41:13 UTC
Red Hat Product Errata RHSA-2026:26709 0 None None None 2026-06-17 17:49:11 UTC
Red Hat Product Errata RHSA-2026:28923 0 None None None 2026-06-24 10:22:52 UTC
Red Hat Product Errata RHSA-2026:29844 0 None None None 2026-06-25 12:55:45 UTC
Red Hat Product Errata RHSA-2026:36083 0 None None None 2026-07-07 05:59:17 UTC
Red Hat Product Errata RHSA-2026:36085 0 None None None 2026-07-07 06:33:52 UTC
Red Hat Product Errata RHSA-2026:36086 0 None None None 2026-07-07 06:09:11 UTC
Red Hat Product Errata RHSA-2026:36087 0 None None None 2026-07-07 06:19:08 UTC
Red Hat Product Errata RHSA-2026:36632 0 None None None 2026-07-08 09:22:49 UTC
Red Hat Product Errata RHSA-2026:36633 0 None None None 2026-07-08 09:12:04 UTC
Red Hat Product Errata RHSA-2026:36634 0 None None None 2026-07-08 09:33:48 UTC
Red Hat Product Errata RHSA-2026:36768 0 None None None 2026-07-08 14:32:55 UTC
Red Hat Product Errata RHSA-2026:36791 0 None None None 2026-07-08 16:11:39 UTC
Red Hat Product Errata RHSA-2026:36792 0 None None None 2026-07-08 16:19:44 UTC
Red Hat Product Errata RHSA-2026:36798 0 None None None 2026-07-08 16:21:56 UTC
Red Hat Product Errata RHSA-2026:38502 0 None None None 2026-07-13 03:22:57 UTC
Red Hat Product Errata RHSA-2026:38810 0 None None None 2026-07-13 09:28:27 UTC

Description OSIDB Bzimport 2026-06-05 08:12:11 UTC 
A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters in SyncChangeCounter().

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/bdd7bf57af208b1ddf57d4683d67104443b44812

Reported via ZDI-CAN-30164 (Trend Micro Zero Day Initiative). Tracking: PSIRTSUPT-16950.
Comment 2 errata-xmlrpc 2026-06-17 12:06:40 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 3 errata-xmlrpc 2026-06-17 14:49:34 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 4 errata-xmlrpc 2026-06-17 15:41:12 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 5 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 6 errata-xmlrpc 2026-06-22 02:25:19 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 7 errata-xmlrpc 2026-06-24 10:22:51 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 8 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 9 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 10 errata-xmlrpc 2026-07-07 06:09:10 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 11 errata-xmlrpc 2026-07-07 06:19:07 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 12 errata-xmlrpc 2026-07-07 06:33:51 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 13 errata-xmlrpc 2026-07-08 09:12:03 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 14 errata-xmlrpc 2026-07-08 09:22:48 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 15 errata-xmlrpc 2026-07-08 09:33:47 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 16 errata-xmlrpc 2026-07-08 14:32:54 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-2026:36768 https://access.redhat.com/errata/RHSA-2026:36768
Comment 17 errata-xmlrpc 2026-07-08 16:11:37 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 18 errata-xmlrpc 2026-07-08 16:19:43 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 19 errata-xmlrpc 2026-07-08 16:21:55 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 20 errata-xmlrpc 2026-07-13 03:22:56 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-2026:38502 https://access.redhat.com/errata/RHSA-2026:38502
Comment 21 errata-xmlrpc 2026-07-13 09:28:26 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
Note You need to log in before you can comment on or make changes to this bug.