Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes_CVE-2026-3298

{
    "lastseen": "",
    "description": "The method \"sock_recvfrom_into()\" of \"asyncio.ProacterEventLoop\" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected.",
    "published": "2026-04-21T14:45:01.919Z",
    "modified": "2026-04-21T14:47:54.591Z",
    "type": "cve",
    "title": "Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes",
    "source": "PSF",
    "references": "https://github.com/python/cpython/pull/148809\nhttps://github.com/python/cpython/issues/148808\nhttps://mail.python.org/archives/list/[email protected]/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/",
    "id": "CVE-2026-3298",
    "bulletinFamily": "",
    "cwe": [
        "CWE-787"
    ],
    "cvelist": null,
    "sourceData": "Python Software Foundation CPython 3.11.0",
    "sourceHref": "",
    "cvss": {
        "score": 8.8,
        "severity": "HIGH",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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            "privilegesRequired": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "CPython",
    "version": "3.11.0",
    "vendor": "Python Software Foundation",
    "ai_description": "Out-of-bounds buffer write vulnerability in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes",
    "ai_severity": "High",
    "ai_vendor": "Python Software Foundation",
    "ai_product": "CPython",
    "ai_version": "3.11.0",
    "ai_score": 8.8
}