X.Org Server Present Extension Use-After-Free Information Disclosure Vulnerability

October 15th, 2026
ZDI-26-760 ZDI-CAN-31830

CVE ID

CVE-2026-93515

CVSS Score

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

Affected Vendors

X.Org

Affected Products

Server

Vulnerability Details

This vulnerability allows local attackers to disclose sensitive information 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 handling of present_window_priv objects. 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 in conjunction with other vulnerabilities to 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/1b6955c3108e

Disclosure Timeline

  • 2026-08-25 - Vulnerability reported to vendor
  • 2026-10-15 - Coordinated public release of advisory
  • 2026-10-15 - Advisory Updated

Credit

Anonymous

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