Published Nov 13, 2026Sources checked Nov 13, 2026
6.9MEDIUMCVSS out of 10
What this means
Review the available evidence
CVE-2026-109904 and is rated Medium severity with a CVSS score of 6.9. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Nov 14, 2026
Release Notes
CISA KEVNot listedBased on the latest collected catalog
EPSSUnavailableNo current score collected
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-109904?
A buffer overread caused by an integer-overflow in Proc/SProcXResQueryClientIds in X.Org xwayland before 24.1.15 and X Server before 21.1.26 could be used by attackers on authenticated X clients to crash the server or leak out information.