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.

CVSS v3 7.8 HIGH

7.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/	Exploit Press/Media Coverage Third Party Advisory
https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac	Patch
https://github.com/nltk/nltk/pull/3465	Issue Tracking Patch
https://github.com/nltk/nltk/releases/tag/3.9.3	Release Notes
https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments	Patch Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-07-24 22:16

Updated : 2026-08-10 13:37

NVD link : CVE-2025-71408

Mitre link : CVE-2025-71408

CVE.ORG link : CVE-2025-71408

JSON object : View

Products Affected

nltk

nltk

CWE

CWE-95

Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

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