CVE-2026-50256 Memory corruption in Red Hat Enterprise Linux 10

High 7.8 Published 5 Jun 2026 Updated 28 Sep 2026

A stack buffer overflow in X.Org X server font alias resolution allows attackers to crash the server or escalate privileges if running as root.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-50256?

CVE-2026-50256 is a high-severity memory corruption vulnerability in Redhat Enterprise Linux, published on 5 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-121

Which versions are affected by CVE-2026-50256?

It affects 3 products.

Products include Redhat Enterprise Linux, X.org X Server, X.org Xwayland.

How do I fix CVE-2026-50256?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-50256 being exploited?

There is no known exploitation of CVE-2026-50256 in the wild and no public exploit code.

All Redhat Enterprise Linux vulnerabilities

Sources

Also known as AZL-89522, AZL-89571, BELL-CVE-2026-50256, DEBIAN-CVE-2026-50256, ECHO-0715-de66-8cf8, GHSA-7gx3-r5q9-6j33 and 1 more.