Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels_CVE-2026-50258

{
    "lastseen": "",
    "description": "A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.",
    "published": "2026-06-05T10:31:39.316Z",
    "modified": "2026-06-05T10:31:39.316Z",
    "type": "cve",
    "title": "Xorg-x11-server: xorg-x11-server-xwayland: xorg-x11-server: stack buffer overflow in xkb key types due to unchecked shift levels",
    "source": "redhat",
    "references": "https://access.redhat.com/security/cve/CVE-2026-50258\nhttps://bugzilla.redhat.com/show_bug.cgi?id=2485383\nhttps://gitlab.freedesktop.org/xorg/xserver/-/commit/543e108516428fc8c3bea91d6563ad266f9a801e\nhttps://lists.x.org/archives/xorg-announce/2026-June/003702.html\nhttps://redhat.atlassian.net/browse/PSIRTSUPT-16950",
    "id": "CVE-2026-50258",
    "bulletinFamily": "",
    "cwe": [
        "CWE-121"
    ],
    "cvelist": null,
    "sourceData": "",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Red Hat Enterprise Linux 10",
    "version": "",
    "vendor": "Red Hat",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}