AWS Lambda now supports cross-account container image pulling from Amazon Elastic Container Registry

AWS Lambda now allows you to create or update your functions with container images stored in an Amazon ECR repository in a different AWS account than that of your AWS Lambda function. Previously, you could only access container images stored in an Amazon ECR repository in the same AWS account as your AWS Lambda functions. If you used a centralized account for your Amazon ECR repositories, you needed to copy your container images into an Amazon ECR repository in the same account as your Lambda function. You can now simplify this workflow by accessing the container image stored in an Amazon ECR repository in a different account. 

Source:: Amazon AWS