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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
ntlk ntlk
Default version status: affected
0 to < 3.9.3affected
pkg:pypi/nltkReferences
- 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 ↗