NLTK up to 3.9.2 collocations collocations.py eval os command injection

Summaryinfo

A vulnerability identified as problematic has been detected in NLTK up to 3.9.2. Affected by this issue is the function eval of the file collocations.py of the component collocations. The manipulation leads to os command injection. This vulnerability is documented as CVE-2025-71408. The attack needs to be performed locally. There is not any exploit available.

Detailsinfo

A vulnerability was found in NLTK up to 3.9.2. It has been rated as problematic. This issue affects the function eval of the file collocations.py of the component collocations. The manipulation with an unknown input leads to a os command injection vulnerability. Using CWE to declare the problem leads to CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at aydinnyunus.github.io. The identification of this vulnerability is CVE-2025-71408 since 07/24/2026. The exploitation is known to be easy. An attack has to be approached locally. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1202 for this issue.

Upgrading to version 3.9.3 eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Name

• NLTK

Version

• 3.9.0
• 3.9.1
• 3.9.2

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion