A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and model poisoning. The downloader extracts package archives into shared namespaces such as `corpora/` and `taggers/` instead of package-isolated roots, and validates package integrity only after the archive has been written and extracted. This design flaw enables one package to overwrite another package's trusted resources within the same namespace, making the changes immediately active through ordinary NLTK APIs. This issue persists across fresh interpreter restarts and can affect downstream workflows, including machine learning pipelines and reproducibility-sensitive environments.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and
    model poisoning. The downloader extracts package archives into shared namespaces such as `corpora/` and
    `taggers/` instead of package-isolated roots, and validates package integrity only after the archive has
    been written and extracted. This design flaw enables one package to overwrite another package's trusted
    resources within the same namespace, making the changes immediately active through ordinary NLTK APIs.
    This issue persists across fresh interpreter restarts and can affect downstream workflows, including
    machine learning pipelines and reproducibility-sensitive environments. (CVE-2026-12261)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and     model poisoning. The downloader extracts package archives into shared namespaces such as `corpora/` and     `taggers/` instead of package-isolated roots, and validates package integrity only after the archive has     been written and extracted. This design flaw enables one package to overwrite another package's trusted     resources within the same namespace, making the changes immediately active through ordinary NLTK APIs.
    This issue persists across fresh interpreter restarts and can affect downstream workflows, including     machine learning pipelines and reproducibility-sensitive environments. (CVE-2026-12261)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
472774	Echo: nltk: security update to 3.10.0	Tenable Cloud Security	Echo Local Security Checks	Local	medium
472774	Echo: nltk: security update to 3.10.0	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	medium
472163	SCA: security update for nltk (GHSA-ffj6-66c4-86gw)	Tenable Cloud Security	SCA Checks	Local	medium
472163	SCA: security update for nltk (GHSA-ffj6-66c4-86gw)	Tenable Self-Hosted Container Security	SCA Checks	Local	medium
333363	Linux Distros Unpatched Vulnerability : CVE-2026-12261	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2026-12261

medium

Tenable Plugins

medium

medium

medium

medium

medium