CVE-2021-21284
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Arch Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Fixed | 1:20.10.3-1 |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 20.10.3+dfsg1-1 |
| sid | Fixed | 20.10.3+dfsg1-1 |
| forky | Fixed | 20.10.3+dfsg1-1 |
| bullseye | Fixed | 20.10.3+dfsg1-1 |
| bookworm | Fixed | 20.10.3+dfsg1-1 |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| Go | github.com/moby/moby | <19.3.15 | 19.3.15 |
| Go | github.com/moby/moby | >=20.10.0-beta1,<20.10.3 | 20.10.3 |
References
- https://security.archlinux.org/ASA-202102-12
- https://security-tracker.debian.org/tracker/CVE-2021-21284
- https://www.suse.com/security/cve/CVE-2021-21284.html
- https://github.com/moby/moby/security/advisories/GHSA-7452-xqpj-6rpc
- https://nvd.nist.gov/vuln/detail/CVE-2021-21284
- https://github.com/moby/moby/commit/64bd4485b3a66a597c02c95f5776395e540b2c7c
- https://docs.docker.com/engine/release-notes/#20103
- https://github.com/moby/moby/releases/tag/v19.03.15
- https://github.com/moby/moby/releases/tag/v20.10.3
- https://security.gentoo.org/glsa/202107-23
- https://security.netapp.com/advisory/ntap-20210226-0005
- https://www.debian.org/security/2021/dsa-4865
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.