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CVE-2026-33999

high

A flaw was found in the X.Org X server.

A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts.

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: 2026-04-23 16:16
Modified: 2026-11-04 23:17
NVD status: Awaiting Analysis
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

Not reported by the source (unknown — not "none").

Weakness classification (CWE)

CWE-191

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

Mitigation & advisories

No vendor advisory or patch reference tagged by NVD. Check the references below.

References

Data sources

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

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