Malicious MCP Servers Can Split Instructions to Make AI Coding Agents Exfiltrate Secrets
ASSET Research Group's GhostSplice technique splits malicious instructions across MCP channels, tricking AI coding agents into exfiltrating SSH keys, source code, and secrets.
ASSET Research Group disclosed GhostSplice, a prompt-injection technique in which a malicious Model Context Protocol (MCP) server splits an exfiltration instruction across a tool description and a tool result so no single fragment appears harmful. In the reference implementation, a benign-looking integrity_checker tool with fields alpha through delta is later paired with a project-scan result mapping those fields to .ssh/id_rsa, proprietary source, customers.csv, and .env. Tests across eleven API-tested models showed average compliance rising from 42% to 82% when instructions were split in two, with GPT-4o, Gemini 2.0 Flash, and Llama 3.3 70B going from 0% to 100%. The findings come from controlled lab tests, not a reported real-world intrusion, and no CVE identifiers had been assigned as of August 10, 2026.