Ysoserial-0.0.4-all.jar Download -

ysoserial is an open-source proof-of-concept utility that generates Java deserialization payloads (serialized objects) that trigger gadget chains in vulnerable libraries or application code when deserialized. Security researchers and penetration testers use it to verify and demonstrate insecure deserialization vulnerabilities (CVE classes and application-level misconfigurations). The tool produces payloads that can execute commands, open network connections, or perform other actions when a vulnerable application blindly deserializes untrusted data.

Before you download or use this tool, read this carefully:

The ysoserial tool is intended for legitimate security research, authorized penetration testing, and educational purposes only. Unauthorized use of this tool against systems you do not own or lack explicit permission to test is illegal in most jurisdictions. The author(s) of this article and the tool itself are not responsible for any misuse. Always adhere to responsible disclosure and relevant laws (e.g., CFAA in the US, Computer Misuse Act in the UK). ysoserial-0.0.4-all.jar download

If you are a developer, using this tool on your own applications is an excellent way to test your deserialization defenses.

Implement resolveClass() to block dangerous classes like Runtime, ProcessBuilder, or known gadget classes. The ysoserial tool is intended for legitimate security

Warning: ysoserial is a security research tool designed to generate payloads that exploit insecure Java deserialization. It can be used for legitimate security testing but also for malicious purposes. Only download, run, or use it in environments where you have explicit permission to test. Do not use it against systems you do not own or have authorization to assess.

ysoserial is a proof-of-concept tool that generates Java deserialization payloads. It exploits the fact that many Java libraries and applications deserialize untrusted data without proper validation. The tool chains together various "gadget chains"—existing classes and methods in common Java libraries (like Apache Commons Collections, Spring, Groovy, etc.)—to execute arbitrary commands or code. If you are a developer, using this tool

The name "ysoserial" is a play on "JSON serialization," but its real power lies in binary Java serialization.

Since this is a standard Java artifact, it is archived on Maven Central. This is the most reliable source for unaltered binaries.

Version 0.0.4 was released around 2015-2016 and became a gold standard for several reasons:

Newer versions exist (e.g., 0.0.6), but 0.0.4 remains beloved for its simplicity and reliability in legacy environments.