PYSEC-2026-3735

    Dashboard / Vulnerabilities / PYSEC-2026-3735

    PYSEC-2026-3735

    Published: 25 Aug 2026Last Modified: 1 Sept 2026

    Summary:

    Details: NLTK versions before 3.10.3 contain a remote code execution vulnerability in allowlisted pickle loaders that trust entire module namespaces instead of specific safe callables. Attackers can craft malicious pickle payloads invoking dangerous in-namespace functions like ReppTokenizer._execute and numpy.f2py.crackfortran.myeval through pickle REDUCE to execute arbitrary commands during model or tokenizer artifact loading.

    References: https://www.vulncheck.com/advisories/nltk-before-3.10.3-remote-code-execution-via-unsafe-pickle-deserialization, https://github.com/nltk/nltk/security/advisories/GHSA-x99w-6fgc-pmfw

    Affected packages

    Package

    Name: nltk

    Purl: pkg:pypi/nltk

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -3.10.3

    Affected versions

    0.8

    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
    PYSEC-2026-3735 | CVE-DB