“This could occur by running a malicious image or by building a container image using a malicious Dockerfile or upstream image”
Snyk found four container escapes in runc and Docker’s build tools, including one built around the WORKDIR command. A poisoned upstream image is enough to reach the host. The disclosure went to Docker on December 11 and the runc fix shipped January 31. Every CI pipeline that pulls a random base image and builds it as root just learned what “isolation” was worth.