runc through 1.0.0-rc8, as used in Docker through 19.03.2-ce and other products, allows AppArmor restriction bypass because libcontainer/rootfs_linux.go incorrectly checks mount targets, and thus a malicious Docker image can mount over a /proc directory. A flaw was found in runc. An attacker who controls the container image for two containers that share a volume can race volume mounts during container initialization, by adding a symlink to the rootfs that points to a directory on the volume. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability