High severity · published Mar 20, 2026
CVE-2026-33231
NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app
7.5
CVSS
1.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.2% · higher than 69% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NL
nltk · nltk
<= 3.9.3 · source: vendor, NVD
LC
Lightspeed Core · Red Hat
All versions, or not specified · source: CISA
OL
OpenShift Lightspeed · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Ansible Automation Platform 2 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI (RHOAI) · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI 2.25 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat OpenShift AI 3.3 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33231
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33231
Patch
https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b
Exploit
https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:19712
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:24977
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:37275
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:65126
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