Use-After-Free Flaw in X.Org X Server and Xwayland
CVE-2026-50261

7.8HIGH

What is CVE-2026-50261?

A use-after-free vulnerability has been identified in the X.Org X server and Xwayland's SyncChangeCounter() function. This flaw allows an attacker to exploit the behavior of SyncCounters when managed by concurrent client connections. By destroying multiple SyncCounters, an unauthorized client may manipulate memory, potentially leading to server instability or unauthorized privilege escalation when the X server operates with root permissions. Mitigation measures are advised to protect against possible exploitation.

Affected Version(s)

Red Hat Enterprise Linux 10 0:24.1.9-4.el10_2.2

Red Hat Enterprise Linux 10.0 Extended Update Support 0:24.1.5-6.el10_0.1

Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:1.20.4-35.el7_9

References

CVSS V3.1

Score:
7.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Upstream acknowledges Anonymous (Trend Micro Zero Day Initiative) as the original reporter.
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