CVE-2025-71408
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| ntlk | ntlk | 0 < 3.9.3 | affected |
Weaknesses
- CWE-95: Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
References
- https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/
- https://github.com/nltk/nltk/releases/tag/3.9.3
- https://github.com/nltk/nltk/pull/3465
- https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac
- https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments
Feedback
Was this page helpful?
Glad to hear it! Please tell us how we can improve.
Sorry to hear that. Please tell us how we can improve.