Container escape via mount-target symlink exchange

Directory traversal in Open Container Initiative runc 1.0.0-rc94 and earlier allows attackers to escape a container and access host files. During container startup, runc sanitizes a mount destination before use, but a second container can exchange that checked path for a symlink, causing later mounts to resolve a host path and bind-mount the host root into the container. Exploitation requires permission to start containers, malicious code in a container sharing the volume, and a specific multi-mount configuration; confinement can limit resulting host data access and modification but does not block the breakout.