CVE-2024-11218: Buildah allows build breakout using malicious Containerfiles and concurrent builds

With careful use of the --mount flag in RUN instructions in Containerfiles, and by using either multi-stage builds with use of concurrently-executing build stages (e.g., using the --jobs CLI flag) or multiple separate but concurrently-executing builds, a malicious Containerfile can be used to expose content from the build host to the command being run using the RUN instruction. This can be used to read or write contents using the privileges of the process which is performing the build. When that process is a root-owned podman system service which is provided for use by unprivileged users, this includes the ability to read and write contents which the client should not be allowed to read and write, including setuid executables in locations where they can be later accessed by unprivileged users.