---
id: CVE-2026-109956
title: >-
  NLTK through 3.10.3 contains a path traversal vulnerability in WekaClassifier
  that allows attackers to bypass nltk.pathsec containment by supplying
  unvalidated model paths
summary: >-
  NLTK through 3.10.3 contains a path traversal vulnerability in WekaClassifier
  that allows attackers to bypass nltk.pathsec containment by supplying
  unvalidated model paths. Attackers controlling the model_filename or model
  argument can m…
severity: high
cvss: 7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L'
cwe:
  - CWE-22
published: '2026-10-13'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T14:17:34.520'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109956'
references:
  - url: 'https://github.com/nltk/nltk/security/advisories/GHSA-j456-xh4h-cpf2'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nltk-through-3.10.3-path-traversal-via-wekaclassifier-model-path
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-109956.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-109956'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2550515'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-109956'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109956'
  - url: 'https://github.com/nltk/nltk/pull/3863'
  - url: >-
      https://github.com/nltk/nltk/commit/6a17606293fe9d3ea1006f99dd3fed2e2b25d519
  - url: 'https://github.com/nltk/nltk'
  - url: 'https://github.com/nltk/nltk/releases/tag/v3.10.4'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
  - cve.org
  - exploit-available
  - osv
  - pip
ingestedAt: '2026-10-13T14:29:01.855Z'
vendor: Red Hat
product: Red Hat OpenShift AI (RHOAI)
affected:
  - lightspeed_core
  - openshift_lightspeed
  - ansible_automation_platform 2
  - openshift_ai_rhoai
epss: 0.00318
epssPercentile: 0.24586
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-26T19:46:23.846442Z'
aliases:
  - GHSA-j456-xh4h-cpf2
ecosystem: pip
patched:
  - nltk 3.10.4
scores:
  nvd: 7
  osv: 8.6
---

## Overview

NLTK through 3.10.3 contains a path traversal vulnerability in WekaClassifier that allows attackers to bypass nltk.pathsec containment by supplying unvalidated model paths. Attackers controlling the model_filename or model argument can make the weka JVM write files via -d or probe files via -l outside allowed data roots.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Lightspeed Core, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat OpenShift AI (RHOAI) · no fix planned: Red Hat Ansible Automation Platform 2, Lightspeed Core, OpenShift Lightspeed, Red Hat OpenShift AI (RHOAI) · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-109956.json)

## Package advisory (CVE-2026-109956)

Affected packages:

- `nltk < 3.10.4`

Patched in:

- `nltk 3.10.4`

Source: https://osv.dev/vulnerability/GHSA-j456-xh4h-cpf2