id: PYSEC-2026-2235
published: "2026-03-20T23:16:46.680Z"
modified: "2026-07-13T05:50:16.639938Z"
aliases:
- CVE-2026-33230
- GHSA-gfwx-w7gr-fvh7
details: 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:
- package:
    name: nltk
    ecosystem: PyPI
    purl: pkg:pypi/nltk
  ranges:
  - type: ECOSYSTEM
    events:
    - introduced: "0"
    - fixed: 3.9.4
  versions:
  - "0.8"
  - "0.9"
  - 0.9.3
  - 0.9.4
  - 0.9.5
  - 0.9.6
  - 0.9.7
  - 0.9.8
  - 0.9.9
  - 2.0.1
  - 2.0.1rc1
  - 2.0.1rc2-git
  - 2.0.1rc3
  - 2.0.1rc4
  - 2.0.2
  - 2.0.3
  - 2.0.4
  - 2.0.5
  - 2.0b4
  - 2.0b5
  - 2.0b6
  - 2.0b7
  - 2.0b8
  - 2.0b9
  - 3.0.0
  - 3.0.0b1
  - 3.0.0b2
  - 3.0.1
  - 3.0.2
  - 3.0.3
  - 3.0.4
  - 3.0.5
  - "3.1"
  - "3.2"
  - 3.2.1
  - 3.2.2
  - 3.2.3
  - 3.2.4
  - 3.2.5
  - "3.3"
  - "3.4"
  - 3.4.1
  - 3.4.2
  - 3.4.3
  - 3.4.4
  - 3.4.5
  - "3.5"
  - 3.5b1
  - "3.6"
  - 3.6.1
  - 3.6.2
  - 3.6.3
  - 3.6.4
  - 3.6.5
  - 3.6.6
  - 3.6.7
  - "3.7"
  - "3.8"
  - 3.8.1
  - "3.9"
  - 3.9.1
  - 3.9.2
  - 3.9.3
  - 3.9b1
  ecosystem_specific: {}
references:
- type: FIX
  url: https://github.com/nltk/nltk/commit/1c3f799607eeb088cab2491dcf806ae83c29ad8f
- type: FIX
  url: https://github.com/nltk/nltk/commit/40d0bc1d484a3458d6a63ecb5ba4957ab16ba14e
- type: EVIDENCE
  url: https://github.com/nltk/nltk/security/advisories/GHSA-gfwx-w7gr-fvh7
severity:
- type: CVSS_V3
  score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N