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CVE-2026-50259

high

A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland.

Vendor / product: X.org — x server

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
7.8 (CVSS v3.1)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity source: NVD CVSS v3.1 (secalert@redhat.com)
Timeline (UTC)
Published: 2026-06-05 12:16
Modified: 2026-11-04 23:17
NVD status: Modified
Last synced 1 hour ago
Verified against the source API 2026-11-04 23:38 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

x.org / x_server <21.1.23
x.org / xwayland <24.1.12
redhat / enterprise_linux 7.0, 8.0, 9.0, 10.0

Weakness classification (CWE)

CWE-121

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Patch / mitigation: https://gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b

References

Data sources

NVD CVE API 2.0 — fetched 2026-11-04 23:38 UTC · record ↗

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Related CVEs

CVE-2026-50264CVE-2026-50261CVE-2026-50260CVE-2026-50258CVE-2026-50257