CVE-2026-50258 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 allows attackers to crash the server or escalate privileges via unchecked shift levels in key types.

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-2026-50258?

CVE-2026-50258 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. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. 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-2026-50258?

It affects 3 products.

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

How do I fix CVE-2026-50258?

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-2026-50258 being exploited?

There is no known exploitation of CVE-2026-50258 in the wild and no public exploit code.

All Redhat Enterprise Linux vulnerabilities

Sources

Also known as AZL-89525, AZL-89586, BELL-CVE-2026-50258, DEBIAN-CVE-2026-50258, ECHO-a1e4-1c3c-5a65, GHSA-74fp-pmv2-rh3f and 1 more.