In Docker before versions 9.03.15, 20.10.3 there is a vulnerability involving the –userns-remap option in which access to remapped root allows privilege escalation to real root.

When using “–userns-remap”, if the root user in the remapped namespace has access to the host filesystem they can modify files under “” that cause writing files with extended privileges.

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

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