Advisory Details

June 9th, 2026

X.Org Server CheckSetGeom Out-Of-Bounds Read Information Disclosure Vulnerability

ZDI-26-334
ZDI-CAN-28679

CVE ID CVE-2026-34000
CVSS SCORE 6.1, AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
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 key names. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated data structure. 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/81b6a34f
DISCLOSURE TIMELINE
  • 2026-02-17 - Vulnerability reported to vendor
  • 2026-06-09 - Coordinated public release of advisory
  • 2026-06-09 - Advisory Updated
CREDIT Jan-Niklas Sohn
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