Yes, it[1] is[2] a[3] real[4] issue[5] which leads to privilege escalation bugs. It also doesn't help that most containers that Docker is responsible for managing is supposed to be unprivileged, and Docker itself is commonly used as a component for a multi-tenant container runtime.
[1] https://www.cvedetails.com/cve/CVE-2019-15752/
[2] https://www.cvedetails.com/cve/CVE-2019-14271/
[3] https://www.cvedetails.com/cve/CVE-2019-5736/
[4] https://www.cvedetails.com/cve/CVE-2018-15664/
[5] https://www.cvedetails.com/cve/CVE-2018-15514/