Create a custom AWS CloudFormation public registry extension. Reference a GitHub repository that hosts the open source modules in the extension.

Create an Amazon CloudFront distribution with an Amazon S3 bucket as the origin. Upload the patched modules to Amazon S3 when needed. Modify each Lambda function to download the patched modules during the cold start.

Launch an Amazon EC2 instance. Host a private open source module registry on the EC2 instance. Upload the modified open source modules to the private registry. Modify deployment scripts to download from the private registry.

Create a Lambda layer with the open source modules. Modify all three Lambda functions to depend on the layer. Remove the open source modules from each Lambda function. Patch the Lambda layer and update the Lambda functions to reference the new layer version.