A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling attackers to traverse directories and access sensitive files on the server. This issue is particularly critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs, chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to remote code execution when combined with other vulnerabilities.

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

  - A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal
    in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and
    BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling
    attackers to traverse directories and access sensitive files on the server. This issue is particularly
    critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs,
    chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to
    sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to
    remote code execution when combined with other vulnerabilities. (CVE-2026-0847)

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.

  - A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal     in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and     BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling     attackers to traverse directories and access sensitive files on the server. This issue is particularly     critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs,     chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to     sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to     remote code execution when combined with other vulnerabilities. (CVE-2026-0847)

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

ID	Name	Product	Family	Type	Severity
465336	Echo: nltk: security update to 3.9.3	Tenable Cloud Security	Echo Local Security Checks	Local	high
465336	Echo: nltk: security update to 3.9.3	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
301115	Linux Distros Unpatched Vulnerability : CVE-2026-0847	Nessus	Misc.	Local	high

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