CVE-2025-71408
Medium
Elevated severity or exploit probability.
CVSS base
7.8
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS — probability of exploitation (30 days)
0.2%
10.0th percentile
CISA KEV
Not listed
Weakness / dates
CWE-95
Published 2026-07-24 · modified 2026-08-10
CVSS breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | L | Local |
| Attack Complexity | L | Low |
| Privileges Required | L | Low |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | H | High |
| Integrity | H | High |
| Availability | H | High |
Timeline
- 2026-07-24 — Published (NVD)
- 2026-08-10 — Last modified (NVD)
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.
Affected
References
- exploit https://aydinnyunus.github.io/2026/06/07/command-injection-nltk-collocations-eval/
- https://github.com/nltk/nltk/commit/66f14096d952ec8f04934f515e027534bd4eb0ac
- https://github.com/nltk/nltk/pull/3465
- https://github.com/nltk/nltk/releases/tag/3.9.3
- https://www.vulncheck.com/advisories/nltk-eval-injection-via-collocations-py-command-line-arguments