When running the AWS Serverless Application Model Command Line Interface (SAM CLI) build process with Docker and symlinks are included in the build files, the container environment allows a user to access privileged files on the host by leveraging the elevated permissions granted to the tool. A user could leverage the elevated permissions to access restricted files via symlinks and copy them to a more permissive location on the container.
Users should upgrade to v1.133.0 or newer and ensure any forked or derivative code is patched to incorporate the new fixes.
The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.