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 "/var/lib/docker/<remapping>" that cause writing files with extended privileges. Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user.
{
"versions": [
{
"introduced": "0"
},
{
"fixed": "19.03.15"
},
{
"introduced": "20.0.0"
},
{
"fixed": "20.10.3"
}
]
}