---
id: CVE-2026-33236
title: >-
  NLTK (Natural Language Toolkit) is a suite of open source Python modules, data
  sets, and tutorials supporting research and development in Natural Language
  Processing
summary: >-
  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, the NLTK downloader does not validate
  the…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H'
cwe:
  - CWE-22
vendor: nltk
product: nltk
affected:
  - nltk <= 3.9.3
published: '2026-03-20'
updated: '2026-07-10'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33236'
references:
  - url: >-
      https://github.com/nltk/nltk/commit/89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a
    label: security-advisories@github.com
  - url: 'https://github.com/nltk/nltk/security/advisories/GHSA-469j-vmhf-r6v7'
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:10184'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:19712'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:37275'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-33236'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2449824'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33236.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33236'
  - url: 'https://github.com/nltk/nltk'
tags:
  - nvd
  - osv
  - pip
epss: 0.00575
epssPercentile: 0.45931
ingestedAt: '2026-07-10T13:03:45.502Z'
aliases:
  - GHSA-469j-vmhf-r6v7
  - PYSEC-2026-2237
ecosystem: pip
---

## Overview

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, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.

## Affected

- `nltk <= 3.9.3`

## Remediation

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

## Package advisory (CVE-2026-33236)

Affected packages:

- `nltk <= 3.9.2`

Source: https://osv.dev/vulnerability/GHSA-469j-vmhf-r6v7