Vulnerability · Published Mar 20, 2026 · Assigned by GitHub_M
CVE-2026-33230nltk Vulnerable to Cross-site Scripting
Medium 6.1
In plain English
A medium-severity cross-site scripting in nltk from nltk. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | nltk | no fix listed | DEBIAN-CVE-2026-33230 |
| Debian:13 | nltk | no fix listed | DEBIAN-CVE-2026-33230 |
| Debian:14 | nltk | 3.10.0-1 | DEBIAN-CVE-2026-33230 |
| PyPI | nltk | 3.9.4 | PYSEC-2026-2235 |
| PyPI | nltk | 3.9.4 | GHSA-gfwx-w7gr-fvh7 |
| Ubuntu:25.10 | nltk | no fix listed | UBUNTU-CVE-2026-33230 |
| Ubuntu:26.10 | nltk | no fix listed | UBUNTU-CVE-2026-33230 |
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N