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    CVE-2026-81727

    NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite files outside the install root through pre-existing hardlinks. Attackers with write access to a shared downloader directory can create hardlinks pointing to outside-root files that are then overwritten during normal package extraction, mutating files outside the intended install tree.

    Published:Aug 27, 2026
    Last Modified:Aug 31, 2026
    EPS:Aug 27, 2026
    EPSS Score:0.00135
    CVSS Score:7.1

    Affected Products

    Vendor
    Nltk
    Product
    Nltk

    Exploits

    https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672

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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High