RCE in Nltk

CVE-2025-71408

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.

EPSS: 0.002 (9.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-71408?
CVE-2025-71408 is a high-severity vulnerability in Nltk, classified under Eval Injection. CVSS score: 7.8/10. Published 2026-07-24.
How severe is CVE-2025-71408?
High severity. CVSS v3 base score is 7.8 out of 10.