---
id: CVE-2026-33231
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, `nltk.app.wordnet_app` allows
  unauthentic…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-306
vendor: nltk
product: nltk
affected:
  - nltk <= 3.9.3
patched:
  - openshift_ai 2.25
  - openshift_ai 3.3
published: '2026-03-20'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T13:19:24.380'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33231'
references:
  - url: >-
      https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b
    label: security-advisories@github.com
  - url: 'https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g'
    label: security-advisories@github.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:19712'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:24977'
    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/errata/RHSA-2026:65126'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-33231'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2449836'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33231.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-33231'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33231'
  - url: 'https://github.com/nltk/nltk'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
  - osv
  - pip
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-03-25T13:43:39.454391Z'
epss: 0.01215
epssPercentile: 0.66752
ingestedAt: '2026-07-10T13:03:45.497Z'
aliases:
  - GHSA-jm6w-m3j8-898g
  - PYSEC-2026-2236
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, `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.

## Affected

- `nltk <= 3.9.3`

## Remediation

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

## Vendor advisories

- **RHSA-2026:24977** · Red Hat · fixed in: Red Hat OpenShift AI 2.25 · released 2026-06-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:24977)
- **RHSA-2026:65126** · Red Hat · fixed in: Red Hat OpenShift AI 2.25 · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:65126)
- **RHSA-2026:19712** · Red Hat · fixed in: Red Hat OpenShift AI 3.3 · released 2026-05-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:19712)
- **RHSA-2026:37275** · Red Hat · fixed in: Red Hat OpenShift AI 3.3 · released 2026-07-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:37275)
- **Red Hat VEX** · Important · affected: Lightspeed Core, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat OpenShift AI (RHOAI) · no fix planned: OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Lightspeed Core, Red Hat OpenShift AI (RHOAI) · updated 2026-09-08 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33231.json)

## Package advisory (CVE-2026-33231)

Affected packages:

- `nltk < 3.9.4`

Patched in:

- `nltk 3.9.4`

Source: https://osv.dev/vulnerability/GHSA-jm6w-m3j8-898g