CVE-2026-33231
Unauthenticated Remote Shutdown Vulnerability in NLTK WordNet Server
Publication date: 2026-03-20
Last updated on: 2026-03-23
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| nltk | nltk | to 3.9.3 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-306 | The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the Natural Language Toolkit (NLTK) versions 3.9.3 and prior, specifically in the wordnet_app module. When the local WordNet Browser HTTP server is started in its default mode, an unauthenticated remote attacker can send a simple HTTP GET request with the path /SHUTDOWN%20THE%20SERVER. This request causes the server process to terminate immediately by calling os._exit(0), resulting in a denial of service.
How can this vulnerability impact me? :
The impact of this vulnerability is a denial of service (DoS). An attacker can remotely and without authentication shut down the local WordNet Browser HTTP server, causing it to stop functioning abruptly. This can disrupt any services or applications relying on this server, leading to potential downtime and loss of availability.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, update NLTK to a version later than 3.9.3 where the issue has been patched (commit bbaae83db86a0f49e00f5b0db44a7254c268de9b).
Alternatively, avoid running the WordNet Browser HTTP server in its default mode or restrict access to it to trusted users only to prevent unauthenticated remote shutdown.