Container escape is a security risk in which malicious players can leverage a containerized application’s vulnerabilities to breach its isolation boundary, gaining access to the host system’s resources. Once an attacker accesses the host system, they can escalate their privilege to access other containers running in the machine or run harmful code on the host. Depending on how vulnerable the host is, the actor could also access other hosts in the network.
Recently, researchers from Positive Security published findings identifying a major remote code execution (RCE) vulnerability in dompdf, a popular PDF generation library. In their reporting, they outlined a way that code could be loaded into an application and then remotely executed during a PDF being generated. Dompdf is used quite extensively within the PHP ecosystem, and is used within over 59,000 open sourced platforms and projects.