CVE-2021-21284

Published: 2 February 2021

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.

Priority

Cvss 3 Severity Score

6.8

Score breakdown

Status

Package	Release	Status
docker.io Launchpad, Ubuntu, Debian	bionic	Released (20.10.7-0ubuntu1~18.04.1)
	focal	Released (20.10.7-0ubuntu1~20.04.1)
	groovy	Ignored (end of life)
	hirsute	Released (20.10.7-0ubuntu1~21.04.1)
	impish	Not vulnerable (20.10.7-0ubuntu1)
	jammy	Not vulnerable (20.10.7-0ubuntu1)
	kinetic	Not vulnerable (20.10.7-0ubuntu1)
	lunar	Not vulnerable (20.10.7-0ubuntu1)
	mantic	Not vulnerable (20.10.7-0ubuntu1)
	trusty	Does not exist
	upstream	Released (20.10.3)
	xenial	Needed

Severity score breakdown

Parameter	Value
Base score	6.8
Attack vector	Adjacent
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Changed
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

References

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