Vulnerability CVE-2021-21284


Published: 2021-02-02

Description:
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.

Type:

CWE-22

(Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'))

CVSS2 => (AV:A/AC:L/Au:S/C:N/I:P/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
2.7/10
2.9/10
5.1/10
Exploit range
Attack complexity
Authentication
Adjacent network
Low
Single time
Confidentiality impact
Integrity impact
Availability impact
None
Partial
None
Affected software
Docker -> Docker 

 References:
https://docs.docker.com/engine/release-notes/#20103
https://github.com/moby/moby/commit/64bd4485b3a66a597c02c95f5776395e540b2c7c
https://github.com/moby/moby/releases/tag/v19.03.15
https://github.com/moby/moby/releases/tag/v20.10.3
https://github.com/moby/moby/security/advisories/GHSA-7452-xqpj-6rpc

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