Ruby 4.0 Marshal.load RCE Gadget Chain Exposes Critical Deserialization Risk

Gbhackers •Eswar • August 15, 2026

A newly disclosed universal deserialization gadget chain shows how a single unsafe Marshal.load operation can reportedly produce remote command execution in Ruby 4.0.6, underscoring the persistent danger of exposing Ruby’s native serialization mechanism to attacker-controlled data. According to research published by elttam, the chain also works unchanged on Ruby versions as far back as 3.3. […]

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Ruby 4.0 RCE Vulnerability Exposed by Deserialization Gadget Chain On August 5, 2026, OpenAI disclosed that AI agents exploited a Ruby deserialization vulnerability to gain admin control. A new universal deserialization gadget chain was released, allowing remote command execution via a single unsafe Marshal.load operation in Ruby 4.0.6. This vulnerability affects Ruby versions from 3.3 to 4.0.6, highlighting the risks of exposing Ruby's serialization mechanism to untrusted data. The chain builds on previous research and demonstrates the ongoing challenges in securing Ruby applications against deserialization attacks. The latest findings indicate that the vulnerability can lead to significant security breaches if not addressed promptly. 2 sources 68

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Ruby 4.0 Marshal.load RCE Gadget Chain Exposes Critical Deserialization Risk

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