S3 buckets can be versioned. When the S3 bucket is unversioned it means that a new version of an object overwrites an existing one in the S3 bucket.

It can lead to unintentional or intentional information loss.

Ask Yourself Whether

• The bucket stores information that require high availability.

There is a risk if you answered yes to any of those questions.

Recommended Secure Coding Practices

It’s recommended to enable S3 versioning and thus to have the possibility to retrieve and restore different versions of an object.

Sensitive Code Example

bucket = s3.Bucket(self, "bucket",
    versioned=False       # Sensitive
)

The default value of versioned is False so the absence of this parameter is also sensitive.

Compliant Solution

bucket = s3.Bucket(self, "bucket",
    versioned=True
)

See

• OWASP Top 10 2021 Category A5 - Security Misconfiguration
• OWASP Top 10 2017 Category A6 - Security Misconfiguration
• AWS documentation - Using versioning in S3 buckets
• AWS CDK version 2 - Using versioning in S3 buckets