---
title: "CVE-2026-109956: NLTK - Path Traversal"
description: "NLTK through 3.10.3 contains a path traversal vulnerability caused by unvalidated model paths in WekaClassifier, letting attackers write or probe files outside allowed data roots, exploit requires control over model_filename or model argument."
url: https://panop.io/threat-heartbeat/CVE-2026-109956/
---

# CVE-2026-109956 NLTK - Path Traversal

NLTK through 3.10.3 contains a path traversal vulnerability caused by unvalidated model paths in WekaClassifier, letting attackers write or probe files outside allowed data roots, exploit requires control over model\_filename or model argument.

CVSS base score 7.0 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.32% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-109956)

## Details

Type

Path Traversal

Impact

File System Write, File System Read

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L

Published

13 October 2026

Updated

15 October 2026

Weakness

[CWE-22](https://cwe.mitre.org/data/definitions/22.html)

## Vendor fix

Update to a version later than 3.10.3 or latest available version.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-109956](https://nvd.nist.gov/vuln/detail/CVE-2026-109956)
- [https://github.com/nltk/nltk/security/advisories/GHSA-j456-xh4h-cpf2](https://github.com/nltk/nltk/security/advisories/GHSA-j456-xh4h-cpf2)
- [https://www.vulncheck.com/advisories/nltk-through-3.10.3-path-traversal-via-wekaclassifier-model-path](https://www.vulncheck.com/advisories/nltk-through-3.10.3-path-traversal-via-wekaclassifier-model-path)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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