CVE-2026-50259

CVE-2026-50259 · Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb setmap request via mapwidths indexing

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This page shows selected source facts. See the linked advisories for the complete description and affected versions.

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.

CVSS 7.8 · High · EPSS 0.2% · Fix available

Published

2026-06-05T10:31:39.152Z

Updated

2026-09-28T11:46:10.666Z

Stack: system

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