What’s Vulnerable › Vulnerabilities

CVE-2026-33231: NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-20 · updated 2026-09-09
• Weakness: CWE-306

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` 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.

Affected products

• nltk: through 3.9.3

References

• https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b
• https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g
• https://access.redhat.com/errata/RHSA-2026:19712
• https://access.redhat.com/errata/RHSA-2026:24977
• https://access.redhat.com/errata/RHSA-2026:37275
• https://access.redhat.com/errata/RHSA-2026:65126
• https://access.redhat.com/security/cve/CVE-2026-33231
• https://bugzilla.redhat.com/show_bug.cgi?id=2449836
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33231.json

Get alerted when CVE-2026-33231 or the next vulnerability affects your stack