What are the biggest security mistakes businesses make?

The most consequential security mistakes businesses make are: using default or weak admin credentials on CMS platforms, failing to update CMS core, plugins, and server dependencies promptly when security patches are released, and storing sensitive data (passwords, API keys, customer PII) without encryption in databases or configuration files.

Other critical failures include not enabling multi-factor authentication on admin accounts, using shared hosting environments where a compromised neighboring site can affect the entire server, not maintaining tested backup and recovery procedures (discovering that backups are corrupted only when a restore is urgently needed is a common and catastrophic situation), and granting excessive database or server permissions to application accounts, violating the principle of least privilege. Many of these mistakes require minimal effort to correct but are consistently overlooked until an incident forces remediation under pressure.