| # DL4J Arbitrary Class Instantiation Vulnerability PoC |
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| ## Vulnerability Summary |
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| **Type:** Arbitrary Class Instantiation via Unvalidated Model Configuration |
| **Severity:** Critical (Remote Code Execution) |
| **Affected Component:** `org.deeplearning4j.models.embeddings.loader.WordVectorSerializer` |
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| ## Vulnerable Code |
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| File: `deeplearning4j/deeplearning4j-nlp-parent/deeplearning4j-nlp/src/main/java/org/deeplearning4j/models/embeddings/loader/WordVectorSerializer.java` |
| Lines: 3067-3069 |
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| ```java |
| String tokenizerFactoryClassName = configuration.getTokenizerFactory(); |
| TokenizerFactory factory = DL4JClassLoading.createNewInstance(tokenizerFactoryClassName); |
| ``` |
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| ## Attack Vector |
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| Attacker creates a malicious Word2Vec model (.zip) with tokenizerFactory pointing to arbitrary Java classes like java.lang.ProcessBuilder. |
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| ## Impact |
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| - Remote Code Execution (RCE) |
| - Arbitrary Class Instantiation |
| - Denial of Service |
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| ## Remediation |
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| Implement class allowlist for tokenizer factory classes. |
