CVE-2026-50257

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.
References
Link Resource
https://access.redhat.com/errata/RHSA-2026:26562
https://access.redhat.com/errata/RHSA-2026:26566
https://access.redhat.com/errata/RHSA-2026:26590
https://access.redhat.com/errata/RHSA-2026:26610
https://access.redhat.com/errata/RHSA-2026:26709
https://access.redhat.com/errata/RHSA-2026:28923
https://access.redhat.com/errata/RHSA-2026:29844
https://access.redhat.com/errata/RHSA-2026:36083
https://access.redhat.com/errata/RHSA-2026:36085
https://access.redhat.com/errata/RHSA-2026:36086
https://access.redhat.com/errata/RHSA-2026:36087
https://access.redhat.com/errata/RHSA-2026:36632
https://access.redhat.com/errata/RHSA-2026:36633
https://access.redhat.com/errata/RHSA-2026:36634
https://access.redhat.com/errata/RHSA-2026:36768
https://access.redhat.com/errata/RHSA-2026:36791
https://access.redhat.com/errata/RHSA-2026:36792
https://access.redhat.com/errata/RHSA-2026:36798
https://access.redhat.com/errata/RHSA-2026:38502
https://access.redhat.com/errata/RHSA-2026:38810
https://access.redhat.com/errata/RHSA-2026:46377
https://access.redhat.com/errata/RHSA-2026:46382
https://access.redhat.com/errata/RHSA-2026:46385
https://access.redhat.com/errata/RHSA-2026:46392
https://access.redhat.com/errata/RHSA-2026:46456
https://access.redhat.com/errata/RHSA-2026:46460
https://access.redhat.com/errata/RHSA-2026:46473
https://access.redhat.com/security/cve/CVE-2026-50257 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2485382 Issue Tracking Third Party Advisory
https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b Patch
https://lists.x.org/archives/xorg-announce/2026-June/003702.html Mailing List Third Party Advisory
https://redhat.atlassian.net/browse/PSIRTSUPT-16950 Permissions Required
https://access.redhat.com/errata/RHSA-2026:26562
https://access.redhat.com/errata/RHSA-2026:26566
https://access.redhat.com/errata/RHSA-2026:26590
https://access.redhat.com/errata/RHSA-2026:26610
https://access.redhat.com/errata/RHSA-2026:26709
https://access.redhat.com/errata/RHSA-2026:28923
https://access.redhat.com/errata/RHSA-2026:29844
https://access.redhat.com/errata/RHSA-2026:36083
https://access.redhat.com/errata/RHSA-2026:36085
https://access.redhat.com/errata/RHSA-2026:36086
https://access.redhat.com/errata/RHSA-2026:36087
https://access.redhat.com/errata/RHSA-2026:36632
https://access.redhat.com/errata/RHSA-2026:36633
https://access.redhat.com/errata/RHSA-2026:36634
https://access.redhat.com/errata/RHSA-2026:36768
https://access.redhat.com/errata/RHSA-2026:36791
https://access.redhat.com/errata/RHSA-2026:36792
https://access.redhat.com/errata/RHSA-2026:36798
https://access.redhat.com/errata/RHSA-2026:38502
https://access.redhat.com/errata/RHSA-2026:38810
https://access.redhat.com/errata/RHSA-2026:46377
https://access.redhat.com/errata/RHSA-2026:46382
https://access.redhat.com/errata/RHSA-2026:46385
https://access.redhat.com/errata/RHSA-2026:46392
https://access.redhat.com/errata/RHSA-2026:46456
https://access.redhat.com/errata/RHSA-2026:46460
https://access.redhat.com/errata/RHSA-2026:46473
https://access.redhat.com/security/cve/CVE-2026-50257 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2485382 Issue Tracking Third Party Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50257.json
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

History

27 Jul 2026, 13:18

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References () https://access.redhat.com/errata/RHSA-2026:46377 - () https://access.redhat.com/errata/RHSA-2026:46377 -
References () https://access.redhat.com/errata/RHSA-2026:46382 - () https://access.redhat.com/errata/RHSA-2026:46382 -
References () https://access.redhat.com/errata/RHSA-2026:46385 - () https://access.redhat.com/errata/RHSA-2026:46385 -
References () https://access.redhat.com/errata/RHSA-2026:46392 - () https://access.redhat.com/errata/RHSA-2026:46392 -
References () https://access.redhat.com/errata/RHSA-2026:46456 - () https://access.redhat.com/errata/RHSA-2026:46456 -
References () https://access.redhat.com/errata/RHSA-2026:46460 - () https://access.redhat.com/errata/RHSA-2026:46460 -
References () https://access.redhat.com/errata/RHSA-2026:46473 - () https://access.redhat.com/errata/RHSA-2026:46473 -

27 Jul 2026, 10:16

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  • () https://access.redhat.com/errata/RHSA-2026:46385 -
  • () https://access.redhat.com/errata/RHSA-2026:46392 -
  • () https://access.redhat.com/errata/RHSA-2026:46473 -

27 Jul 2026, 08:16

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  • () https://access.redhat.com/errata/RHSA-2026:46460 -

27 Jul 2026, 07:16

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27 Jul 2026, 04:17

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  • () https://access.redhat.com/errata/RHSA-2026:46382 -

13 Jul 2026, 13:16

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References () https://access.redhat.com/errata/RHSA-2026:38502 - () https://access.redhat.com/errata/RHSA-2026:38502 -
References () https://access.redhat.com/errata/RHSA-2026:38810 - () https://access.redhat.com/errata/RHSA-2026:38810 -

13 Jul 2026, 12:16

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References
  • () https://access.redhat.com/errata/RHSA-2026:38810 -

13 Jul 2026, 06:16

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References
  • () https://access.redhat.com/errata/RHSA-2026:38502 -

09 Jul 2026, 13:17

Type Values Removed Values Added
References () https://access.redhat.com/errata/RHSA-2026:36768 - () https://access.redhat.com/errata/RHSA-2026:36768 -
References () https://access.redhat.com/errata/RHSA-2026:36791 - () https://access.redhat.com/errata/RHSA-2026:36791 -
References () https://access.redhat.com/errata/RHSA-2026:36792 - () https://access.redhat.com/errata/RHSA-2026:36792 -
References () https://access.redhat.com/errata/RHSA-2026:36798 - () https://access.redhat.com/errata/RHSA-2026:36798 -

09 Jul 2026, 04:17

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  • () https://access.redhat.com/errata/RHSA-2026:36768 -
  • () https://access.redhat.com/errata/RHSA-2026:36798 -

08 Jul 2026, 17:17

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References
  • () https://access.redhat.com/errata/RHSA-2026:36791 -
  • () https://access.redhat.com/errata/RHSA-2026:36792 -

08 Jul 2026, 13:16

Type Values Removed Values Added
References () https://access.redhat.com/errata/RHSA-2026:36632 - () https://access.redhat.com/errata/RHSA-2026:36632 -
References () https://access.redhat.com/errata/RHSA-2026:36633 - () https://access.redhat.com/errata/RHSA-2026:36633 -
References () https://access.redhat.com/errata/RHSA-2026:36634 - () https://access.redhat.com/errata/RHSA-2026:36634 -

08 Jul 2026, 10:16

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References
  • () https://access.redhat.com/errata/RHSA-2026:36632 -
  • () https://access.redhat.com/errata/RHSA-2026:36633 -
  • () https://access.redhat.com/errata/RHSA-2026:36634 -

07 Jul 2026, 12:16

Type Values Removed Values Added
References
  • () https://access.redhat.com/errata/RHSA-2026:36083 -
  • () https://access.redhat.com/errata/RHSA-2026:36085 -
  • () https://access.redhat.com/errata/RHSA-2026:36087 -
References () https://access.redhat.com/errata/RHSA-2026:36086 - () https://access.redhat.com/errata/RHSA-2026:36086 -

07 Jul 2026, 08:16

Type Values Removed Values Added
References
  • () https://access.redhat.com/errata/RHSA-2026:36086 -

30 Jun 2026, 03:20

Type Values Removed Values Added
References
  • () https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-50257.json -
References () https://access.redhat.com/errata/RHSA-2026:26562 - () https://access.redhat.com/errata/RHSA-2026:26562 -
References () https://access.redhat.com/errata/RHSA-2026:26566 - () https://access.redhat.com/errata/RHSA-2026:26566 -
References () https://access.redhat.com/errata/RHSA-2026:26590 - () https://access.redhat.com/errata/RHSA-2026:26590 -
References () https://access.redhat.com/errata/RHSA-2026:26610 - () https://access.redhat.com/errata/RHSA-2026:26610 -
References () https://access.redhat.com/errata/RHSA-2026:26709 - () https://access.redhat.com/errata/RHSA-2026:26709 -
References () https://access.redhat.com/errata/RHSA-2026:28923 - () https://access.redhat.com/errata/RHSA-2026:28923 -
References () https://access.redhat.com/errata/RHSA-2026:29844 - () https://access.redhat.com/errata/RHSA-2026:29844 -
References () https://access.redhat.com/security/cve/CVE-2026-50257 - Third Party Advisory () https://access.redhat.com/security/cve/CVE-2026-50257 - Third Party Advisory
References () https://bugzilla.redhat.com/show_bug.cgi?id=2485382 - Issue Tracking, Third Party Advisory () https://bugzilla.redhat.com/show_bug.cgi?id=2485382 - Issue Tracking, Third Party Advisory

25 Jun 2026, 14:16

Type Values Removed Values Added
References
  • () https://access.redhat.com/errata/RHSA-2026:29844 -

24 Jun 2026, 11:16

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References
  • () https://access.redhat.com/errata/RHSA-2026:28923 -

22 Jun 2026, 08:17

Type Values Removed Values Added
References
  • () https://access.redhat.com/errata/RHSA-2026:26566 -

18 Jun 2026, 02:16

Type Values Removed Values Added
References
  • () https://access.redhat.com/errata/RHSA-2026:26562 -
  • () https://access.redhat.com/errata/RHSA-2026:26590 -
  • () https://access.redhat.com/errata/RHSA-2026:26610 -
  • () https://access.redhat.com/errata/RHSA-2026:26709 -

08 Jun 2026, 16:45

Type Values Removed Values Added
CPE cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
First Time Redhat enterprise Linux
Redhat
X.org
X.org xwayland
X.org x Server
References () https://access.redhat.com/security/cve/CVE-2026-50257 - () https://access.redhat.com/security/cve/CVE-2026-50257 - Third Party Advisory
References () https://bugzilla.redhat.com/show_bug.cgi?id=2485382 - () https://bugzilla.redhat.com/show_bug.cgi?id=2485382 - Issue Tracking, Third Party Advisory
References () https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b - () https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b - Patch
References () https://lists.x.org/archives/xorg-announce/2026-June/003702.html - () https://lists.x.org/archives/xorg-announce/2026-June/003702.html - Mailing List, Third Party Advisory
References () https://redhat.atlassian.net/browse/PSIRTSUPT-16950 - () https://redhat.atlassian.net/browse/PSIRTSUPT-16950 - Permissions Required

05 Jun 2026, 12:16

Type Values Removed Values Added
New CVE

Information

Published : 2026-06-05 12:16

Updated : 2026-07-27 13:18


NVD link : CVE-2026-50257

Mitre link : CVE-2026-50257

CVE.ORG link : CVE-2026-50257


JSON object : View

Products Affected

x.org

  • x_server
  • xwayland

redhat

  • enterprise_linux
CWE
CWE-416

Use After Free