CVE-2025-71408 ntlk CVE debrief

Who should care

Users of NLTK versions before 3.9.3 should be aware of this vulnerability and take steps to mitigate it, especially those using the nltk.collocations module. This includes developers, security teams, and operators who use NLTK in their applications or infrastructure. The vulnerability's high CVSS score of 8.5 indicates a high severity, and users should exercise caution when using the nltk.collocations module, especially with untrusted command-line arguments.

Technical summary

The nltk.collocations module in NLTK versions before 3.9.3 contains an eval injection vulnerability. When collocations.py is invoked directly, it passes command-line arguments to eval() without validation or sanitization, allowing an attacker to execute arbitrary Python code, including OS commands via the os module. This vulnerability has a high CVSS score of 8.5, indicating a high severity. The vulnerability is tracked by CVE-2025-71408 and is currently in the 'Received' state on the NVD.

Defensive priority

High priority due to the high CVSS score of 8.5 and the potential for arbitrary code execution.

Recommended defensive actions

• Upgrade to NLTK version 3.9.3 or later
• Avoid invoking collocations.py directly with untrusted command-line arguments
• Implement input validation and sanitization for command-line arguments
• Monitor for suspicious activity related to NLTK usage
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability was reported by an unknown source and is tracked by CVE-2025-71408. The NVD entry is currently in the 'Received' state. Evidence is limited, and defenders should verify the vulnerability's existence and impact. The eval injection vulnerability in the nltk.collocations module allows an attacker to execute arbitrary Python code, including OS commands via the os module. Users should exercise caution when using the nltk.collocations module, especially with untrusted command-line arguments.

Official resources