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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-50257 Detail

Description

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://access.redhat.com/security/cve/CVE-2026-50257 Red Hat, Inc. Third Party Advisory 
https://bugzilla.redhat.com/show_bug.cgi?id=2485382 Red Hat, Inc. Issue Tracking  Third Party Advisory 
https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b Red Hat, Inc. Patch 
https://lists.x.org/archives/xorg-announce/2026-June/003702.html Red Hat, Inc. Mailing List  Third Party Advisory 
https://redhat.atlassian.net/browse/PSIRTSUPT-16950 Red Hat, Inc. Permissions Required 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-416 Use After Free Red Hat, Inc.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-50257
NVD Published Date:
06/05/2026
NVD Last Modified:
06/08/2026
Source:
Red Hat, Inc.