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` contains a reflected cross-site scripting issue in the `lookup_...` route. A crafted `lookup_<payload>` URL can inject arbitrary HTML/JavaScript into the response page because attacker-controlled `word` data is reflected into HTML without escaping. This impacts users running the local WordNet Browser server and can lead to script execution in the browser origin of that application. Commit 1c3f799607eeb088cab2491dcf806ae83c29ad8f fixes the issue.
History

Tue, 24 Mar 2026 02:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 23 Mar 2026 19:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*

Mon, 23 Mar 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Mon, 23 Mar 2026 10:00:00 +0000

Type Values Removed Values Added
First Time appeared Nltk
Nltk nltk
Vendors & Products Nltk
Nltk nltk

Fri, 20 Mar 2026 23:00:00 +0000


Fri, 20 Mar 2026 22:45:00 +0000

Type Values Removed Values Added
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` contains a reflected cross-site scripting issue in the `lookup_...` route. A crafted `lookup_<payload>` URL can inject arbitrary HTML/JavaScript into the response page because attacker-controlled `word` data is reflected into HTML without escaping. This impacts users running the local WordNet Browser server and can lead to script execution in the browser origin of that application. Commit 1c3f799607eeb088cab2491dcf806ae83c29ad8f fixes the issue.
Title nltk Vulnerable to Cross-site Scripting
Weaknesses CWE-79
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-03-20T22:43:39.621Z

Updated: 2026-03-24T02:07:12.001Z

Reserved: 2026-03-18T02:42:27.507Z

Link: CVE-2026-33230

cve-icon Vulnrichment

Updated: 2026-03-24T02:07:06.975Z

cve-icon NVD

Status : Analyzed

Published: 2026-03-20T23:16:46.680

Modified: 2026-03-23T19:14:50.023

Link: CVE-2026-33230

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-03-20T22:43:39Z

Links: CVE-2026-33230 - Bugzilla