A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). 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. This may be used to crash the server, or for privilege escalation if the X server runs as root.

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00012.

Exploitation none

Automatable no

Technical Impact total

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Red Hat Red Hat Enterprise Linux 10 affected —
Red Hat Red Hat Enterprise Linux 6 unknown —
Red Hat Red Hat Enterprise Linux 7 affected —
Red Hat Red Hat Enterprise Linux 8 affected —
Red Hat Red Hat Enterprise Linux 8 affected —
Red Hat Red Hat Enterprise Linux 9 affected —
Red Hat Red Hat Enterprise Linux 9 affected —

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://access.redhat.com/security/cve/CVE-2026-50261 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2485386 cve-icon cve-icon
https://gitlab.freedesktop.org/xorg/xserver/-/commit/bdd7bf57af208b1ddf57d4683d67104443b44812 cve-icon cve-icon cve-icon
https://lists.x.org/archives/xorg-announce/2026-June/003702.html cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-50261 cve-icon
https://redhat.atlassian.net/browse/PSIRTSUPT-16950 cve-icon cve-icon cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-50261 cve-icon
History

Fri, 05 Jun 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Fri, 05 Jun 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Important

Fri, 05 Jun 2026 11:45:00 +0000

Type Values Removed Values Added
Description A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). 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. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Title Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: use-after-free in syncchangecounter()
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-416
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-06-05T12:38:54.542Z

Reserved: 2026-06-04T14:55:24.012Z

Link: CVE-2026-50261

cve-icon Vulnrichment

Updated: 2026-06-05T12:38:49.241Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-06-05T12:16:39.617

Modified: 2026-06-05T13:27:38.750

Link: CVE-2026-50261

cve-icon Redhat

Severity : Important

Publid Date: 2026-06-02T00:00:00Z

Links: CVE-2026-50261 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-05T12:30:40Z

Weaknesses