CVE-2019-14751 — NLTK Downloader before 3

NLTK Downloader before 3.4.5 is vulnerable to a directory traversal, allowing attackers to write arbitrary files via a ../ (dot dot slash) in an NLTK package (ZIP archive) that is mishandled during extraction.

01What is this vulnerability?

NLTK Downloader before 3.4.5 is vulnerable to a directory traversal, allowing attackers to write arbitrary files via a ../ (dot dot slash) in an NLTK package (ZIP archive) that is mishandled during extraction.

02Affected products

Vendor	Product	Versions
n	a / n/a	n/a

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2019-08-22T15:59:59.000Z
• Last modified: 2024-08-05T00:26:38.633Z

09References

• github.com — https://github.com/nltk/nltk/blob/3.4.5/ChangeLog
• github.com — https://github.com/nltk/nltk/commit/f59d7ed8df2e0e957f7f247fe218032abdbe9a10
• salvatoresecurity.com — https://salvatoresecurity.com/zip-slip-in-nltk-cve-2019-14751/
• github.com — https://github.com/mssalvatore/CVE-2019-14751_PoC
• lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
• lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00054.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00001.html