TI-2026-25649 Aliases CVE-2026-33230 GHSA-gfwx-w7gr-fvh7

nltk Vulnerable to Cross-site Scripting

MEDIUM 60CWE-79Published 2026-03-20 · Updated 2026-03-24

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: Low · Low · None
Fix status: Partial Red Hat: 4 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-79.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00344 28th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial nltk (PyPI): 3.9.4Red Hat: 4 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
nltk	nltk	up to 3.9.3	—	No fix listed	CNA
—	nltk (PyPI)	before 3.9.4	3.9.4	Patch available	GHSA-gfwx-w7gr-fvh7

nltk Vendornltk Affected up to 3.9.3 Fixed in — No fix listed CNA
nltk (PyPI) Vendor— Affected before 3.9.4 Fixed in 3.9.4 Patch available GHSA-gfwx-w7gr-fvh7

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:nltk:nltk::::::::	up to 3.9.3	Vulnerable	nltk

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* Versions up to 3.9.3 Vulnerable ·nltk

Remediation

Fix · GHSA-gfwx-w7gr-fvh7 nltk (PyPI) Fixed in 3.9.4 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Lightspeed Core	Affected	No fix yet: Fix deferred
OpenShift Lightspeed	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-33230
2026-10-03 Alias added: GHSA-gfwx-w7gr-fvh7

References

Exploit 1

https://github.com/nltk/nltk/security/advisories/GHSA-gfwx-w7gr-fvh7

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-33230

Other 1

https://github.com/nltk/nltk

TI-2026-00629 Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading CVSS 3.0CRITICAL 10.0
TI-2025-12800 Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution CVSS 3.0CRITICAL 10.0
TI-2026-55173 NLTK before 3.10.3 JVM Argument Injection via Per-Call Options CVSS 4.0CRITICAL 9.3
TI-2026-55155 NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization CVSS 4.0CRITICAL 9.3
TI-2026-56370 nltk PorterStemmer before 3.10.3 Quadratic-time DoS CVSS 4.0HIGH 8.7
TI-2026-55172 NLTK 3.10.2 Path Traversal via corpus-reader constructors CVSS 4.0HIGH 8.8

See all 41 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences