Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nltk | 3.4.5-1 | — |
| Debian 13 | nltk | 3.4.5-1 | — |
| Debian 12 | nltk | 3.4.5-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | nltk | 3.2.5-1ubuntu0.1 | USN-4106-1 |
| Ubuntu 16.04 LTS | nltk | 3.1-1ubuntu0.1 | USN-4106-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 14.04 LTS | nltk | 2.0~b9-0ubuntu4.1~esm2 | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP2 | python-nltk | 3.7-bp152.3.3.1 | openSUSE-SU-2022:10040-1 |
| SUSE Package Hub 15 SP1 | python-nltk | 3.4.5-bp151.4.3.1 | openSUSE-SU-2020:0440-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-nltk | 3.5-1.10 | openSUSE-SU-2026:11469-1, openSUSE-SU-2024:14103-1, openSUSE-SU-2024:11241-1 |
| openSUSE Leap 15.1 | python-nltk | 3.4.5-lp151.4.3.1 | openSUSE-SU-2020:0436-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
mssalvatore/CVE-2019-14751_PoC ★ 4 · Aug 9, 2019
A Proof of Concept for CVE-2019-14751
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | nltk | < 3.4.5 | 3.4.5 | GHSA-mr7p-25v2-35wr |
Advisories 7
- openSUSE-SU-2026:11469-1 python313-nltk-3.10.1-1.1 on GA media SUSE / openSUSE Security Updates · Aug 7, 2026
- USN-4106-1 NLTK vulnerability Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2024:11241-1 python36-nltk-3.5-1.10 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:0436-1 Security update for python-nltk SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:14103-1 python310-nltk-3.8.1-2.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:0440-1 Security update for python-nltk SUSE / openSUSE Security Updates · May 7, 2025
- openSUSE-SU-2022:10040-1 Security update for python-nltk SUSE / openSUSE Security Updates · May 7, 2025
References
- https://github.com/nltk/nltk/blob/3.4.5/ChangeLog
- https://github.com/nltk/nltk/commit/f59d7ed8df2e0e957f7f247fe218032abdbe9a10
- https://salvatoresecurity.com/zip-slip-in-nltk-cve-2019-14751/
- https://github.com/mssalvatore/CVE-2019-14751_PoC
- FEDORA-2020-1b90085f8d vendor-advisory
- FEDORA-2020-0f785235bb vendor-advisory
- openSUSE-SU-2020:0436 vendor-advisory
- openSUSE-SU-2020:0440 vendor-advisory