NLTK vulnerable to Eval Injection via collocations CLI arguments (CVE-2025-71408)
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.
AI Analysis
Technical Summary
The vulnerability in NLTK before version 3.9.3 is an eval injection in the nltk.collocations module. When collocations.py is run directly, the __main__ block uses eval() on command-line arguments as suffixes of BigramAssocMeasures without any allowlist or sanitization. This allows an attacker controlling the command-line arguments to inject and execute arbitrary Python code, including operating system commands through the os module. This is classified as CWE-95 (Improper Control of Generation of Code).
Potential Impact
An attacker with the ability to supply command-line arguments to the vulnerable module can execute arbitrary Python code on the system. This can lead to full code execution, including running OS commands, potentially compromising the host environment. The vulnerability requires local or limited access (local vector) and low complexity to exploit, with no user interaction needed. It has a high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
A fixed version is available starting from NLTK version 3.9.3. Users should upgrade to version 3.9.3 or later to remediate this vulnerability. No other mitigations are indicated. Patch status is not explicitly confirmed in the provided data, but the vulnerability is described as fixed in version 3.9.3, so upgrading to this version or later is recommended.
NLTK vulnerable to Eval Injection via collocations CLI arguments (CVE-2025-71408)
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.
CVSS v3.1
Score 7.8high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in NLTK before version 3.9.3 is an eval injection in the nltk.collocations module. When collocations.py is run directly, the __main__ block uses eval() on command-line arguments as suffixes of BigramAssocMeasures without any allowlist or sanitization. This allows an attacker controlling the command-line arguments to inject and execute arbitrary Python code, including operating system commands through the os module. This is classified as CWE-95 (Improper Control of Generation of Code).
Potential Impact
An attacker with the ability to supply command-line arguments to the vulnerable module can execute arbitrary Python code on the system. This can lead to full code execution, including running OS commands, potentially compromising the host environment. The vulnerability requires local or limited access (local vector) and low complexity to exploit, with no user interaction needed. It has a high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
A fixed version is available starting from NLTK version 3.9.3. Users should upgrade to version 3.9.3 or later to remediate this vulnerability. No other mitigations are indicated. Patch status is not explicitly confirmed in the provided data, but the vulnerability is described as fixed in version 3.9.3, so upgrading to this version or later is recommended.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-848c-c2cx-j7qx
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2025-71408"]
- Ecosystems
- []
- Database Specific Severity
- HIGH
- Cvss Version
- 4.0
Threat ID: 6a6542169c2644c7f8087919
Added to database: 07/25/2026, 23:09:10 UTC
Last enriched: 07/25/2026, 23:48:07 UTC
Last updated: 09/07/2026, 10:52:06 UTC
Views: 58
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