GHSA-5gh2-94qg-qppq

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    GHSA-5gh2-94qg-qppq

    Published: 22 Aug 2026Last Modified: 10 Sept 2026

    Summary: NLTK AllowlistUnpickler dotted-name validation bypass allows remote code execution

    Details: NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.

    References: https://nvd.nist.gov/vuln/detail/CVE-2026-71513, https://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805ea, https://github.com/nltk/nltk, https://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124, https://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypass

    Affected packages

    Package

    Name: nltk

    Purl: pkg:pypi/nltk

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 3.10.0
    Fixed -3.10.3

    Affected versions

    3.10.0
    3.10.1
    3.10.2

    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
    GHSA-5gh2-94qg-qppq | CVE-DB