CVE-2025-71408

Name	CVE-2025-71408
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
nltk (PTS)	bullseye	3.5-1	vulnerable
	bookworm	3.8-1	vulnerable
	trixie	3.9.1-2	vulnerable
	forky, sid	3.10.0-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
nltk	source	(unstable)	3.9.3-1

Notes

https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/
https://github.com/nltk/nltk/pull/3465
Fixed by: https://github.com/nltk/nltk/commit/e373c8c3d10e236672ef65c38ca7d24612941553 (3.9.3)