CVE intelligence

CVE-2026-34001

Vulnerability intelligence

Published Apr 23, 2026Sources checked Nov 11, 2026

7.8HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-34001 and is rated High severity with a CVSS score of 7.8. 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: Sep 25, 2026

Release Notes CBL-Mariner Releases

Vendor-listed releases

24.1.6-4

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-34001?

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function.

An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.

Source: NVD