Impact

When using --userns-remap, if the root user in the remapped namespace has access to the host filesystem they can modify files under /var/lib/docker/<remapping> that cause writing files with extended privileges.

Patches

Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user.

Credits

Maintainers would like to thank Alex Chapman for discovering the vulnerability; @awprice, @nathanburrell, @raulgomis, @chris-walz, @erin-jensby, @bassmatt, @mark-adams, @dbaxa for working on it and Zac Ellis for responsibly disclosing it to security@docker.com

Impact

Pulling an intentionally malformed Docker image manifest crashes the dockerd daemon.

Patches

Versions 20.10.3 and 19.03.15 contain patches that prevent the daemon from crashing.

Credits

Maintainers would like to thank Josh Larsen, Ian Coldwater, Duffie Cooley, Rory McCune for working on the vulnerability and Brad Geesaman for responsibly disclosing it to security@docker.com.