Code Execution via llms.txt in Claude, Codex, and Hermes AI Agents
Security researchers have identified a critical vulnerability allowing Remote Code Execution (RCE) in Anthropic's Claude, OpenAI's Codex, and Nous Research's Hermes AI agents. By exploiting the llms.txt and llms-full.txt standards, attackers employ indirect prompt injection to embed malicious instructions within machine-readable documentation. These agents treat external llms.txt files as high-integrity system instructions rather than passive data, leading to the execution of unauthorized shell commands and API calls. This flaw has been validated via proof-of-concept (PoC) attacks within several Fortune 500 corporate environments, bypassing traditional perimeter security by leveraging the trusted identity of the AI agent to install unowned code.