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Advisory details: pypa / nltk/PYSEC-2026-2235
Advisory ID pypa/nltk/PYSEC-2026-2235
Aliases CVE-2026-33230
GHSA-gfwx-w7gr-fvh7
PYSEC-2026-2235
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.
Status Published
Exploitability 0.5
Weighted Severity 5.5
Risk 2.8
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (0)
There are no known CWE.
System Score Found at
cvssv3.1 6.1 https://github.com/pypa/advisory-database/blob/main/vulns/nltk/PYSEC-2026-2235.yaml
Reference id Reference type URL
1c3f799607eeb088cab2491dcf806ae83c29ad8f Other https://github.com/nltk/nltk/commit/1c3f799607eeb088cab2491dcf806ae83c29ad8f
40d0bc1d484a3458d6a63ecb5ba4957ab16ba14e Other https://github.com/nltk/nltk/commit/40d0bc1d484a3458d6a63ecb5ba4957ab16ba14e
GHSA-gfwx-w7gr-fvh7 Other https://github.com/nltk/nltk/security/advisories/GHSA-gfwx-w7gr-fvh7
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://github.com/pypa/advisory-database/blob/main/vulns/nltk/PYSEC-2026-2235.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

Vector: SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-24T02:06:58Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/33xxx/CVE-2026-33230.json

Source Advisory: vulnrichment/CVE-2026-33230

View SSVC decision tree 
[{'Exploitation': 'poc'},
 {'Automatable': 'no'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]