Vulnerabilities
Misconfiguration
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CVE Vulnerabilities

CVE-2026-50261

Use After Free

Published: Jun 05, 2026 | Modified: Jun 25, 2026
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
7.8 IMPORTANT
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-50261
CWEhttps://cwe.mitre.org/data/definitions/416.html

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.

Weakness

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

NameVendorStart VersionEnd Version
X_serverX.org*21.1.23 (excluding)
XwaylandX.org*24.1.12 (excluding)
Enterprise_linuxRedhat7.0 (including)7.0 (including)
Enterprise_linuxRedhat8.0 (including)8.0 (including)
Enterprise_linuxRedhat9.0 (including)9.0 (including)
Enterprise_linuxRedhat10.0 (including)10.0 (including)
Red Hat Enterprise Linux 10RedHatxorg-x11-server-Xwayland-0:24.1.9-4.el10_2.2*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-Xwayland-0:21.1.3-20.el8_10.2*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-0:1.20.11-28.el8_10.2*
Red Hat Enterprise Linux 8RedHattigervnc-0:1.15.0-10.el8_10*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.2*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-0:1.20.11-34.el9_8.2*
Red Hat Enterprise Linux 9RedHattigervnc-0:1.15.0-7.el9_8.2*
XwaylandUbuntuupstream*

Potential Mitigations

References

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