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Fencer Intel
high 7.5

CVE-2026-33231 json

NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app

published 7mo ago modified last mo. also GHSA-jm6w-m3j8-898g , PYSEC-2026-2236 , EUVD-2026-13885

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

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 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.

Patch / fix

  • pypi nltk 3.9.4
  • Red Hat Red Hat OpenShift AI 2.25 1780069222, 1780069226, 1787330903
  • Red Hat Red Hat OpenShift AI 3.3 1778262893, 1778263054, 1782471606
  • nltk Debian 14 3.10.0-1

debian advisories DEBIAN-CVE-2026-33231

  • nltk Ubuntu Pro 14.04 LTS 2.0~b9-0ubuntu4.1~esm6
  • nltk Ubuntu Pro 16.04 LTS 3.1-1ubuntu0.1+esm4
  • nltk Ubuntu Pro 18.04 LTS 3.2.5-1ubuntu0.1+esm4
  • nltk Ubuntu Pro 20.04 LTS 3.4.5-2ubuntu0.1~esm4
  • nltk Ubuntu Pro 22.04 LTS 3.7-1ubuntu0.1~esm2
  • nltk Ubuntu Pro 24.04 LTS 3.8.1-1ubuntu0.1~esm2
  • nltk Ubuntu Pro 26.04 LTS 3.9.2-1ubuntu0.1~esm2

ubuntu advisories UBUNTU-CVE-2026-33231

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-33231 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-33231 updated cvss 7.5

nltk: NLTK: Denial of Service via unauthenticated remote shutdown

  • Red Hat Lightspeed Core lightspeed-core/rag-tool-rhel9, lightspeed-core/lightspeed-stack-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-service-api-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-25/de-minimal-rhel9, ansible-automation-platform-26/ee-minimal-rhel9, ansible-automation-platform-24/de-supported-rhel8, ansible-automation-platform-25/lightspeed-chatbot-rhel8
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-llama-stack-core-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift AI 2.25 rhoai/odh-ta-lmes-job-rhel9 1787330903, rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 1780069222, rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9 1780069226
    fixed: vendor fix RHSA-2026:24977
  • Red Hat OpenShift AI 3.3 rhoai 1778262893, rhoai 1778263054, rhoai/odh-trustyai-nemo-guardrails-server-rhel9 1782471606, rhoai/odh-trustyai-nemo-guardrails-server-rhel9 1789570674
    fixed: vendor fix RHSA-2026:19712
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform/ee-minimal-rhel8, ansible-automation-platform/ee-minimal-rhel9, ansible-automation-platform-24/de-minimal-rhel8, ansible-automation-platform-24/de-minimal-rhel9, ansible-automation-platform-24/ee-minimal-rhel8, ansible-automation-platform-24/ee-minimal-rhel9, +19 more Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1780513840, rhoai/odh-rhel9-operator 1788331391, rhoai/odh-vllm-cpu-rhel9 1780069252, rhoai/odh-vllm-cpu-rhel9 1786712073, rhoai/odh-dashboard-rhel9 1780467029, rhoai/odh-dashboard-rhel9 1788312226, +145 more Red Hat OpenShift AI 3.3 rhoai 1778239104, rhoai 1778262829, rhoai 1778262856, rhoai 1778262907, rhoai 1778262952, rhoai 1778262982, +238 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
7mo ago

Exploit prediction

1.26% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi nltk
<3.9.4
3.9.4

Affected products

  • nltk nltk
  • Red Hat Red Hat OpenShift AI 2.25
  • Red Hat Red Hat OpenShift AI 3.3
  • Red Hat Lightspeed Core
  • Red Hat OpenShift Lightspeed
  • Red Hat Red Hat Ansible Automation Platform 2
  • Red Hat Red Hat OpenShift AI (RHOAI)

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.