README.md

DL4J Arbitrary Class Instantiation Vulnerability PoC

Vulnerability Summary

Type: Arbitrary Class Instantiation via Unvalidated Model Configuration
Severity: Critical (Remote Code Execution)
Affected Component: org.deeplearning4j.models.embeddings.loader.WordVectorSerializer

Vulnerable Code

File: deeplearning4j/deeplearning4j-nlp-parent/deeplearning4j-nlp/src/main/java/org/deeplearning4j/models/embeddings/loader/WordVectorSerializer.java Lines: 3067-3069

String tokenizerFactoryClassName = configuration.getTokenizerFactory();
TokenizerFactory factory = DL4JClassLoading.createNewInstance(tokenizerFactoryClassName);

Attack Vector

Attacker creates a malicious Word2Vec model (.zip) with tokenizerFactory pointing to arbitrary Java classes like java.lang.ProcessBuilder.

Impact

• Remote Code Execution (RCE)
• Arbitrary Class Instantiation
• Denial of Service

Remediation

Implement class allowlist for tokenizer factory classes.