CVE-2025-71408
NLTK < 3.9.2 Eval Injection via collocations.py Command-Line Arguments
CVSS Score
7.8
EPSS Score
0.0%
EPSS Percentile
0th
NLTK (Natural Language Toolkit) before version 3.9.3 contains an eval injection vulnerability in the nltk.collocations module that allows an attacker who controls command-line arguments to execute arbitrary Python code. When collocations.py is invoked directly, the __main__ block passes command-line arguments directly to eval() as suffixes of BigramAssocMeasures without allowlist validation or sanitization, enabling an attacker to supply a Python expression that escapes the intended attribute lookup and executes arbitrary code including OS commands via the os module.
| CWE | CWE-95 |
| Vendor | ntlk |
| Product | ntlk |
| Published | Jul 24, 2026 |
| Last Updated | Jul 24, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
ntlk / ntlk
0 < 3.9.3
References
aydinnyunus.github.io: https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/ github.com: https://github.com/nltk/nltk/releases/tag/3.9.3 github.com: https://github.com/nltk/nltk/pull/3465 github.com: https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac vulncheck.com: https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments
Credits
Yunus AYDIN