CVE intelligence

CVE-2026-50256

Vulnerability intelligence

Published Jun 5, 2026Sources checked Nov 13, 2026

7.8HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-50256 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: Jun 11, 2026

CBL-Mariner Releases

Vendor-listed releases

24.1.12-1

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-50256?

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution.

The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks.

This may be used to crash the server, or for privilege escalation if the X server runs as root.

Source: NVD