CVE-2026-0847: NLTK arbitrary file read through path traversal in CorpusReader classes

Summary

CVE-2026-0847 affects NLTK versions up to and including 3.9.2. Several CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader, fail to sanitize or validate file paths, which lets an attacker traverse directories and read arbitrary files on the server. The flaw is especially serious where user-controlled file inputs are processed, such as in ML APIs, chatbots, or NLP pipelines, and it can expose system files, SSH private keys, and API tokens. The source notes it may escalate to remote code execution when combined with other vulnerabilities.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• nltkPyPINo LLM dependency detected · 47 tracked dependents

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