NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, `nltk.app.wordnet_app` allows unauthenticated remote shutdown of the local WordNet Browser HTTP server when it is started in its default mode. A simple `GET /SHUTDOWN%20THE%20SERVER` request causes the process to terminate immediately via `os._exit(0)`, resulting in a denial of service. Commit bbaae83db86a0f49e00f5b0db44a7254c268de9b patches the issue.

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

  - NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials
    supporting research and development in Natural Language Processing. In versions 3.9.3 and prior,
    `nltk.app.wordnet_app` allows unauthenticated remote shutdown of the local WordNet Browser HTTP server
    when it is started in its default mode. A simple `GET /SHUTDOWN%20THE%20SERVER` request causes the process
    to terminate immediately via `os._exit(0)`, resulting in a denial of service. Commit
    bbaae83db86a0f49e00f5b0db44a7254c268de9b patches the issue. (CVE-2026-33231)

The version of IBM Cognos Analytics installed on the remote host is 12.0.4 prior to 12.0.4 FP3, or 12.1.x prior to 12.1.3 FP2. It is, therefore, affected by multiple vulnerabilities as referenced in the IBM Security Bulletin No.
7287209:

  - NLTK versions 3.9.2 and prior are vulnerable to arbitrary code execution due to improper input     validation in the StanfordSegmenter module. The module dynamically loads external Java .jar files     without verification or sandboxing. An attacker can supply or replace the JAR file, enabling the     execution of arbitrary Java bytecode at import time. (CVE-2026-0848)

  - The lodash fix for CVE-2021-23337 added validation for the variable option in _.template but did not     apply the same validation to options.imports key names. Both paths flow into the same Function()     constructor sink. When an application passes untrusted input as options.imports key names, an attacker     can inject default-parameter expressions that execute arbitrary code at template compilation time.
    (CVE-2026-4800)

  - cryptography is a package designed to expose cryptographic primitives and recipes to Python developers.
    From 45.0.0 to before 46.0.7, if a non-contiguous buffer was passed to APIs which accepted Python     buffers (e.g. Hash.update()), this could lead to buffer overflows. (CVE-2026-39892)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8302-1 advisory.

    It was discovered that NLTK incorrectly validated file paths when opening files using the nltk.util     module. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-0846)

    It was discovered that NLTK incorrectly validated file paths in multiple CorpusReader classes. An attacker     could possibly use this issue to obtain sensitive information. (CVE-2026-0847)

    It was discovered that NLTK did not properly validate external Java archive files loaded by     StanfordSegmenter. An attacker could possibly use this issue to execute arbitrary code. This issue only     affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS.
    (CVE-2026-0848)

    It was discovered that NLTK's WordNet browser application incorrectly handled user-supplied input. An     attacker could possibly use this issue to perform a cross-site scripting attack. (CVE-2026-33230)

    It was discovered that NLTK's WordNet browser application did not restrict access to the shutdown     endpoint. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-33231)

    It was discovered that NLTK's downloader did not validate path attributes in remote XML index files. An     attacker could possibly use this issue to create or overwrite arbitrary files. (CVE-2026-33236)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

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

  - NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials     supporting research and development in Natural Language Processing. In versions 3.9.3 and prior,     `nltk.app.wordnet_app` allows unauthenticated remote shutdown of the local WordNet Browser HTTP server     when it is started in its default mode. A simple `GET /SHUTDOWN%20THE%20SERVER` request causes the process     to terminate immediately via `os._exit(0)`, resulting in a denial of service. Commit     bbaae83db86a0f49e00f5b0db44a7254c268de9b patches the issue. (CVE-2026-33231)

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

ID	Name	Product	Family	Type	Severity
455227	Echo: nltk: security update to 3.9.4	Tenable Cloud Security	Echo Local Security Checks	Local	high
455227	Echo: nltk: security update to 3.9.4	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
347960	IBM Cognos Analytics 12.0.4 < 12.0.4 FP3 / 12.1.x < 12.1.3 FP2 Multiple Vulnerabilities (7287209)	Nessus	CGI abuses	Remote	high
316734	Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : NLTK vulnerabilities (USN-8302-1)	Nessus	Ubuntu Local Security Checks	Local	high
303260	Linux Distros Unpatched Vulnerability : CVE-2026-33231	Nessus	Misc.	Local	high

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