Auth bypass in Nltk
CVE-2026-33231
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` allows unauthenticated remote shutdown of the local WordNet Browser HTTP server when it is started in its default mode. A simple `GET /SHUTDOWN%20THE%20SERVER` request causes the process to terminate immediately via `os._exit(0)`, resulting in a denial of service. Commit bbaae83db86a0f49e00f5b0db44a7254c268de9b patches the issue.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.015 (72.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 72.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.009 · newest: 0.015 · change: +0.006
Affected products
- Nltk — versions <= 3.9.3
Weakness classification (CWE)
References
- github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g (Exploit, Vendor Advisory)
- github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b (Patch)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-33231?
- CVE-2026-33231 is a high-severity vulnerability in Nltk, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2026-03-20.
- How severe is CVE-2026-33231?
- High severity. CVSS v3 base score is 7.5 out of 10.