Bug 2449836 (CVE-2026-33231)

Summary: CVE-2026-33231 nltk: NLTK: Denial of Service via unauthenticated remote shutdown
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anpicker, bparees, dschmidt, ebourniv, erezende, hasun, jfula, jkoehler, jlanda, jowilson, jwong, kshier, lgallett, lphiri, nyancey, omaciel, ometelka, ptisnovs, sbunciak, simaishi, smcdonal, stcannon, syedriko, teagle, ttakamiy, xdharmai, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in NLTK (Natural Language Toolkit), specifically in the `nltk.app.wordnet_app` component. An unauthenticated remote attacker can exploit this vulnerability by sending a specially crafted GET request to the local WordNet Browser HTTP server when it is running in its default configuration. This action causes the server process to terminate immediately, leading to a denial of service.
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Description OSIDB Bzimport 2026-03-20 23:03:01 UTC
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.