How severe is CVE-2026-33230?

CVE-2026-33230 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-33230 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33230?

CVE-2026-33230 affects Nltk. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33230?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33230 have an EU (EUVD) identifier?

Yes. CVE-2026-33230 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13883.

When was CVE-2026-33230 published?

CVE-2026-33230 was published on 2026-03-20 and last updated on 2026-06-17.

CVE-2026-33230

CVE-2026-33230 is a medium-severity vulnerability in Nltk with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-13883
Weakness: CWE-79
Affected product: Nltk
Published: 2026-03-20
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-33230?: 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.
How severe is CVE-2026-33230?: CVE-2026-33230 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-33230 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33230?: CVE-2026-33230 affects Nltk. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33230?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33230 have an EU (EUVD) identifier?: Yes. CVE-2026-33230 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-13883.
When was CVE-2026-33230 published?: CVE-2026-33230 was published on 2026-03-20 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*

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