Download of code without integrity check in Natural Language Toolkit - #VU141249
Published: August 7, 2026
Vulnerability identifier: #VU141249
CSH Severity: High
CVSS v4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-494
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to inject malicious packages.
The vulnerability exists due to download of code without integrity check in the package downloader in nltk/downloader.py when downloading and extracting packages. A remote attacker can tamper with a downloaded package or supply a crafted package archive to inject malicious packages.
Exploitation may be possible via a man-in-the-middle attack during HTTP downloads, DNS poisoning to redirect requests to an attacker-controlled server, or a race condition on shared filesystems between file replacement and extraction.
Affected software
Natural Language Toolkit
Remediation
Install security update from vendor's website.
Natural Language Toolkit - update to 3.9.3