The SymJack technique, detailed by Adversa AI, weaponizes the inherent trust developers place in AI coding agents by hijacking symlinks and project instruction files to register malicious MCP servers. Unlike prior supply-chain incidents that relied on poisoned dependencies or compromised maintainers, SymJack requires no code commit from the attacker beyond seeding a malicious repository; the agent itself executes the payload under the developer’s privileges. This operationalizes a risk pattern previously discussed only theoretically in 2024 analyses of LLM agent autonomy. Most coverage still frames such attacks as edge cases, yet Adversa’s PoC succeeded across Claude Code, Gemini CLI, Cursor, Grok Build, and Copilot CLI, exposing a systemic failure to treat agent instructions as untrusted input. The original SecurityWeek reporting correctly notes vendor responses but underplays the blast-radius amplification when the technique reaches CI runners holding production secrets—an outcome already demonstrated in the 2020 SolarWinds compromise and the 2024 xz Utils backdoor. A second overlooked vector is nation-state reuse: similar symlink and configuration hijacking patterns appeared in suspected Chinese APT activity targeting developer tooling in 2023. Effective mitigation demands symlink resolution before approval prompts plus explicit sandboxing of MCP servers, measures Anthropic quietly adopted after initial dismissal. Without these controls, the speed advantage of AI agents directly subsidizes attacker dwell time inside critical pipelines.