CVE-2026-50261
Modified Modified - Updated After Analysis
Use-After-Free in X.Org X Server and Xwayland

Publication date: 2026-06-05

Last updated on: 2026-06-25

Assigner: Red Hat, Inc.

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.
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Meta Information
Published
2026-06-05
Last Modified
2026-06-25
Generated
2026-06-25
AI Q&A
2026-06-05
EPSS Evaluated
2026-06-24
NVD
CVE-2026-50261
EUVD
EUVD-2026-34817
Affected Vendors & Products
Showing 6 associated CPEs
Vendor Product Version / Range
redhat enterprise_linux 7.0
redhat enterprise_linux 8.0
redhat enterprise_linux 9.0
redhat enterprise_linux 10.0
x.org x_server to 21.1.23 (exc)
x.org xwayland to 24.1.12 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Executive Summary

CVE-2026-50261 is a use-after-free vulnerability found in the X.Org X server and Xwayland, specifically in the SyncChangeCounter() function.

This flaw occurs when a client sets up multiple SyncCounters and then destroys those counters via a second client connection while changing them, which can trigger the use-after-free condition.

Exploiting this vulnerability allows any connected X client to potentially crash the server or escalate privileges if the X server is running with root privileges.

Impact Analysis

This vulnerability can impact you by allowing an attacker with access to the X server to cause a denial of service through a server crash.

More seriously, if the X server is running with root privileges, an attacker could exploit this flaw to escalate their privileges, potentially gaining unauthorized root access.

Mitigation Strategies

To mitigate this vulnerability, you should update the affected Xorg components to fixed versions.

  • Upgrade xorg-x11-server to version 21.1.23 or later.
  • Upgrade xorg-x11-server-Xwayland to version 24.1.12 or later.

These updates address the use-after-free flaw in the SyncChangeCounter() function and prevent exploitation that could lead to crashes or privilege escalation.

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