aider (aider-chat) automatically loads a .aider.conf.yml configuration file from the root of the git repository it is launched in. A crafted repository can set test-cmd (executed at startup) or lint-cmd (executed on the first file edit), which aider runs through a shell (subprocess with shell=True) without any user confirmation, LLM interaction, or API key. Consequently, a user who clones and runs aider inside an attacker-supplied repository achieves arbitrary command execution on their machine. The behavior is long-standing and was confirmed on 0.86.3.dev (current main).