CVE-2025-71408 | BDVDB-2026-352194 Detail
ntlkntlk
Description#
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.
Impact#
Per CVSS v3.1: confidentiality impact high, integrity impact high, availability impact high. Attack vector: local.
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
Exploit#
History#
- Version 1Record published in the CVE List.
- Version 2Most recent update recorded in the CVE List.