Storing unencrypted data, particularly sensitive information such as customer credit card details, is a significant security vulnerability. It can lead to data breaches and non-compliance with industry standards like the Payment Card Industry Data Security Standard (PCI DSS). Proper encryption of sensitive data at rest is a critical security control to prevent unauthorized access and misuse. Data misclassification refers to incorrect labeling which might not necessarily lead directly to a breach, while a lack of encryption in protocols and insecure ciphers are generally related to data in transit issues.