NLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read_CVE-2026-54293

{
    "lastseen": "",
    "description": "NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Prior to 3.10.0-rc1, nltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK's SECURITY.md and read arbitrary files from the filesystem. While literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path. This vulnerability is fixed in 3.10.0-rc1.",
    "published": "2026-06-22T17:25:05.611Z",
    "modified": "2026-06-22T17:25:05.611Z",
    "type": "cve",
    "title": "NLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read",
    "source": "GitHub_M",
    "references": "https://github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9v\nhttps://github.com/nltk/nltk/pull/3575",
    "id": "CVE-2026-54293",
    "bulletinFamily": "",
    "cwe": [
        "CWE-22"
    ],
    "cvelist": null,
    "sourceData": "nltk nltk < 3.10.0-rc1",
    "sourceHref": "",
    "cvss": {
        "score": 7.5,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
        "version": "3.1"
    },
    "cvss2": [],
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        "baseScore": 0,
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        "confidentialityImpact": "",
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        "cvssV3": {
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    "href": "",
    "category_name": "CVE",
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    "product": "nltk",
    "version": "< 3.10.0-rc1",
    "vendor": "nltk",
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    "ai_score": 0
}