PT-2026-64418 · Ntlk · Ntlk

Yunus Aydin · CVE-2025-71408 · Published 2026-07-24 · Updated 2026-07-24

Mitre

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Exploit

Fix

Eval Injection

Weakness Enumeration

CWE-95

Related Identifiers

CVE-2025-71408

Affected Products

Ntlk

References · 6

• 🔥 https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval · Exploit
• https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2025-71408 · Security Note
• https://github.com/nltk/nltk/releases/tag/3.9.3 · Note
• https://github.com/nltk/nltk/pull/3465 · Note
• https://vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments · Note