CVE-2026-50259: Red Hat Enterprise Linux

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Red Hat Enterprise Linux: version 7.0 only; version 8.0 only; version 9.0 only; version 10.0 only
• X.org X Server: before 21.1.23 (fixed in 21.1.23)
• X.org Xwayland: before 24.1.12 (fixed in 24.1.12)

Published 2026-06-05. Last modified 2026-08-05.