jqwik 1.10.0 Prompt Injection Explained

On May 25, 2026 the maintainer of the Java testing library jqwik published version 1.10.0 that included an ANSI-hidden prompt-injection message intended for AI coding agents to delete tests and code; the message is erased on interactive terminals but remains in raw CI/log streams and could be read by agentic tools. The report covers discovery, impact (projects that resolved net.jqwik:jqwik-engine:1.10.0 and CI systems that captured raw output), detection methods, mitigations (move off 1.10.0, sandbox agents, treat tool output as untrusted), and the maintainer’s subsequent changes in 1.10.1.