2 Laeven and Valencia define a banking crisis as systemic if two conditions are met: (1) significant signs of financial distress in the banking system (as indicated by significant bank runs, losses in the banking  3  On average a bank crisis costs a country 23% of its GDP, while public debt increases by around 12 percent.3 The amounts are higher for advanced economies.
The architecture of a Federal Reserve CBDC would need to be extremely resistant to such threats—and would need to remain resistant as bad actors employ ever-more sophisticated methods and tactics.