Unauthenticated service shutdown via unprotected GET route
Published Jun 17, 2026 · Updated Jun 17, 2026
Missing authentication in NLTK 3.9.3 and earlier allows remote attackers to shut down the WordNet Browser HTTP service. The request handler decodes the path, compares it with the shutdown phrase, and calls os._exit(0) without authenticating the client. Exposure requires the browser to run in its default mode with its listening port reachable; one request terminates the process and interrupts only that service.
Summary
What happened
Missing authentication in NLTK 3.9.3 and earlier allows remote attackers to shut down the WordNet Browser HTTP service. The request handler decodes the path, compares it with the shutdown phrase, and calls os._exit(0) without authenticating the client. Exposure requires the browser to run in its default mode with its listening port reachable; one request terminates the process and interrupts only that service.
The record
- CVE
- CVE-2026-12199
- Published
- Jun 17, 2026
- Updated
- Jun 17, 2026
- Vendor
- NLTK Project
- Product
- NLTK
- Classifications
- CWE-306, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 17, 2026CVE publishedPublication date reported by the CVE source.
- Jun 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=unspecified <=latest
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Unauthenticated WordNet Browser shutdown proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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