Natural Language Toolkit Zip Archive Handling Arbitrary File Write Vulnerability [CVE-2019-14751]

CVE Number – CVE-2019-14751

A vulnerability in the (NLTK) Downloader component could allow an unauthenticated, remote attacker to write arbitrary files on an affected system. The vulnerability exists because the affected software does not properly handle ZIP archives during extraction. An attacker could exploit this vulnerability by extracting a ZIP archive that contains malicious traversal characters. A successful exploit could allow an attacker to write arbitrary files on the system. The vendor has confirmed this vulnerability and released software updates.


  • To exploit this vulnerability, an attacker may need access to the same, internal network in which the targeted system resides. This access requirement may reduce the likelihood of a successful exploit.


  • Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to have network access. Users are advised not to open email messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in email messages are safe, they are advised not to open them.Administrators can help protect affected systems from external attacks by using a solid firewall strategy.Administrators are advised to monitor affected systems.

Vendor Announcements

Fixed Software

  • The vendor has released software updates at the following link: NLTK 3.4.5

Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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