CVE-2026-0847

Description

A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling attackers to traverse directories and access sensitive files on the server. This issue is particularly critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs, chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to remote code execution when combined with other vulnerabilities.

• How can I get the fixes?
• What do statuses mean?
• Patch details

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Patch details

References

• MITRE
• NVD
• Launchpad
• Debian

Related Ubuntu Security Notices (USN)

• USN-8302-1
• NLTK vulnerabilities
• 25 May 2026

Other references

• https://www.cve.org/CVERecord?id=CVE-2026-0847
• https://huntr.com/bounties/fc69914f-36a9-4c18-8503-10013b39f96
• https://huntr.com/bounties/fc69914f-36a9-4c18-8503-10013b39f966
• https://github.com/nltk/nltk/pull/3479
• https://github.com/nltk/nltk/commit/603e34d25a2cad4612185ebfa6bc1c0dcfcfb2ab