CVE-2026-33230
Reflected XSS in NLTK WordNet App Allows Script Execution
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-79 | The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. |
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 Browser application component. It is a reflected cross-site scripting (XSS) issue in the lookup route, where an attacker can craft a URL containing malicious HTML or JavaScript payloads. Because the application reflects user-controlled input into the HTML response without proper escaping, the malicious code can be executed in the browser of anyone accessing that URL.
How can this vulnerability impact me? :
This vulnerability can lead to the execution of arbitrary scripts in the context of the WordNet Browser application running locally. An attacker could exploit this to perform actions such as stealing sensitive information, hijacking user sessions, or performing unauthorized actions within the application. The impact is limited to users running the local WordNet Browser server, but it poses a risk of client-side script execution.
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 fixed (commit 1c3f799607eeb088cab2491dcf806ae83c29ad8f). Avoid running the local WordNet Browser server until the update is applied to prevent reflected cross-site scripting attacks.