CVE-2025-71408
Last modified
CVE-2025-71408 is a high-severity vulnerability rated 8.5/10 on the CVSS scale. 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 estimates a 0.16% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Nltk | Nltk | < 3.9.3 |
References
- https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/Exploit, Press/Media Coverage, Third Party Advisory
- https://github.com/nltk/nltk/pull/3465Issue Tracking, Patch
- https://github.com/nltk/nltk/releases/tag/3.9.3Release Notes
- https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-argumentsPatch, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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