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Vulnerability · Published Mar 20, 2026 · Assigned by GitHub_M

CVE-2026-33231NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app

High 7.5

In plain English

A high-severity missing authentication in nltk from nltk. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 1.3% (higher than 70% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)1.3%top 30.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nltkno fix listedDEBIAN-CVE-2026-33231
Debian:13nltkno fix listedDEBIAN-CVE-2026-33231
Debian:14nltk3.10.0-1DEBIAN-CVE-2026-33231
PyPInltk3.9.4PYSEC-2026-2236
PyPInltk3.9.4GHSA-jm6w-m3j8-898g
Ubuntu:25.10nltkno fix listedUBUNTU-CVE-2026-33231
Ubuntu:26.10nltkno fix listedUBUNTU-CVE-2026-33231

Affected products (as reported)

VendorProductVersions
nltk nltk <= 3.9.3

Weakness: CWE-306 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References