Files
hermes-agent/cli.py
Societus 52a79d99d2 fix(security): TUI approval overlay accepts blind keystrokes, CLI thread-local callback invisible to agent
Two bugs that allow dangerous commands to execute without informed user consent.

TUI (Ink): useInputHandlers consumes the isBlocked return path, but Ink's
EventEmitter delivers keystrokes to ALL registered useInput listeners. The
ApprovalPrompt component receives arrow keys, number keys, and Enter even
though the overlay appears frozen. The user sees no visual feedback, but
keystrokes are processed — allowing blind approval, session-wide auto-approve
(choice "session"), or permanent allowlist writes (choice "always") without
the user knowing.

Discovered while replicating #13618 (TUI approval overlay freezes terminal).

Fix: in useInputHandlers, when overlay.approval/clarify/confirm is active,
only intercept Ctrl+C. All other keys pass through. This makes the overlay
visually responsive so the user can see what they are selecting.

CLI (prompt_toolkit): _callback_tls in terminal_tool.py is threading.local().
set_approval_callback() is called in the main thread during run(), but the
agent executes in a background thread. _get_approval_callback() returns None
in the agent thread, falling back to stdin input() which prompt_toolkit
blocks. The user sees the approval text but cannot respond — the terminal is
unusable until the 60s timeout expires with a default "deny".

Fix: set callbacks inside run_agent() (the thread target), matching the
pattern already used by acp_adapter/server.py. Clear on thread exit to avoid
stale references.

Closes #13618
2026-04-21 14:29:08 -07:00

482 KiB