CVE-2026-50259

High

Description

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.

SeverityHigh

CVSS7.8

Exploit probability—

Product

X.org Xwayland

PublishedJun 5, 2026

First seenJun 5, 2026

Weakness typeCWE-121CWE-121

How to fix

Update

x.org xwayland24.1.12 or later
x.org x_server21.1.23 or later

Patches

gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b

Vendor advisories

Affected products

Product	Affected versions	Fixed in
x.org xwayland	v < 24.1.12	24.1.12
x.org x_server	v < 21.1.23	21.1.23
redhat enterprise_linux	7.0, 8.0, 9.0, 10.0	—

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