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CVE-2026-33231

HIGH CVSS 3.1: 7.5 EPSS 0.04%
Updated Mar 23, 2026
Nltk
Parameter Value
CVSS 7.5 (HIGH)
Affected Versions before 3.9.3
Type CWE-306 (Missing Authentication for Critical Function)
Vendor Nltk
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Nltk Nltk
cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*
<= 3.9.3