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    CVE-2026-78681

    NLTK versions before 3.10.3 use xml.etree.ElementTree to parse XML in multiple modules, which honors entity declarations in document DTDs. Attackers can craft XML payloads with nested entity declarations that expand from hundreds of bytes to megabytes in memory, causing denial of service.

    Published:Aug 25, 2026
    Last Modified:Aug 26, 2026
    EPS:Aug 25, 2026
    EPSS Score:0.00278
    CVSS Score:7.5

    Affected Products

    Vendor
    Nltk
    Product
    Nltk

    Exploits

    https://github.com/nltk/nltk/security/advisories/GHSA-97qj-x29f-37w7

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-197 Exponential Data Expansion

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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