🛡️ CVE-2025-71408 — nltk

🟠 CVSS 7.8 — High ⚠️ Exploit Public CWE-95 OSV
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2025-71408 is recorded against 1 package.

  • nltk (fixed in 3.9.3)

Timeline and source

Published on 24 July 2026 and last revised on 11 August 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Advisory)
github.com (Fix)
github.com (Fix)
www.vulncheck.com (Fix)
aydinnyunus.github.io (Evidence)

Details

Severity HIGH
CVSS Score 7.8
CVSS Vector 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
CWE CWE-95
Public Exploit ⚠️ Yes
Source OSV
Published 2026-07-24
Updated 2026-08-12
Modified 2026-08-11

Affected Packages

Software From version Fixed in
nltk — 3.9.3

Similar Threats

Exploit Protection

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CVE-2025-71408 carries CVSS 7.8 High rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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