LLM on GMO Flatt Security Research

Poisoning Claude Code: One GitHub Issue to Break the Supply Chain

Mon, 01 Jun 2026 00:00:00 +0000

Introduction

Hello, I’m RyotaK ( @ryotkak ), a security researcher at GMO Flatt Security Inc.

After publishing my previous article ( Pwning Claude Code in 8 Different Ways ), I continued investigating Claude-related products and found several more vulnerabilities.

In this article, I will explain a vulnerability in Claude Code’s GitHub Actions that could allow an attacker to compromise any repository that uses the Claude Code workflow, including Anthropic’s own repositories.¹

Note: Variants of the misconfiguration issues described in this article were actively exploited in the wild before this article was published.

Pwning Claude Code in 8 Different Ways

Mon, 12 Jan 2026 00:00:00 +0000

Introduction

Hello, I’m RyotaK (@ryotkak ), a security engineer at GMO Flatt Security Inc.

A few months ago, I came across an interesting behavior while using Claude Code—it executed a command without my approval.

Since I wasn’t using the permission bypass mode, I decided to investigate further to understand why it was able to execute commands without explicit approval.

TL;DR

I discovered 8 ways to execute arbitrary commands in Claude Code without user approval.

LLM App Security: Risk & Prevent for GenAI Development

Wed, 29 Oct 2025 00:00:00 +0000

Introduction

Hello, I’m Sato (@Nick_nick310 ), a security engineer at GMO Flatt Security Inc.

In recent years, the evolution and widespread adoption of Large Language Models (LLM) have been remarkable, and they are being utilized as generative AI in many services and business processes. While LLMs bring significant benefits, new security risks stemming from their characteristics have also been pointed out, making sufficient understanding and countermeasures essential for safe utilization. What kind of security challenges might arise when integrating LLMs into your company’s services and operations?

Securing LLM Function-Calling: Risks & Mitigations for AI Agents

Wed, 29 Oct 2025 00:00:00 +0000

Introduction

Hello. I’m Yamakawa (@dai_shopper3 ), a security engineer at GMO Flatt Security, Inc.

LLMs exhibit high capabilities in various applications such as text generation, summarization, and question answering, but they have several limitations when used alone. Fundamentally, a standalone model only has the function of generating strings in response to input natural language. Therefore, to create an autonomous AI based on an LLM, a means to exchange information with the outside and execute concrete actions is necessary.

Security Risks of LLM Frameworks with Case Studies

Wed, 29 Oct 2025 00:00:00 +0000

Introduction

Hello. I’m Mori (@ei01241 ), a security engineer at GMO Flatt Security, Inc.

In recent years, the evolution of Large Language Models (LLMs) has accelerated the development of a wide range of AI applications, such as chatbots, data analysis/summarization, and autonomous agents. LLM frameworks like LangChain and LlamaIndex abstract LLM collaboration and external data connections to improve development efficiency, but behind this convenience lie new security risks.

In this article, we will explain common vulnerabilities that tend to occur when using or developing LLM frameworks, illustrated with specific CVEs, and learn lessons from each vulnerability. We will also introduce countermeasures that developers should be aware of based on these lessons.