X.Org Server GLX Extension Use-After-Free Privilege Escalation Vulnerability

July 15th, 2026
ZDI-26-405 ZDI-CAN-30561

CVE ID

CVE-2026-56000

CVSS Score

7.8 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected Vendors

X.Org

Affected Products

Server

Vulnerability Details

This vulnerability allows local attackers to escalate privileges on affected installations of X.Org Server. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the CommonMakeCurrent function. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of root.

Additional Details

X.Org has issued an update to correct this vulnerability. More details can be found at:
https://gitlab.freedesktop.org/xorg/xserver/-/commit/2779affbdb4354e894f490e56f962527d6125043

Disclosure Timeline

  • 2026-05-29 - Vulnerability reported to vendor
  • 2026-07-15 - Coordinated public release of advisory
  • 2026-07-15 - Advisory Updated

Credit

Anonymous

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