CVE-2021-21284
MEDIUM6.8EPSS 0.02%moby Access to remapped root allows privilege escalation to real root
Published: 1/31/2024Modified: 3/13/2026
Description
### Impact 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. ### Patches Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user. ### Credits Maintainers would like to thank Alex Chapman for discovering the vulnerability; @awprice, @nathanburrell, @raulgomis, @chris-walz, @erin-jensby, @bassmatt, @mark-adams, @dbaxa for working on it and Zac Ellis for responsibly disclosing it to [email protected]
Affected packages (2)
- Debian/docker.iofrom 0, < 20.10.3+dfsg1-1
- Go/github.com/moby/mobyfrom 0, < 19.3.15
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.8 | CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N |
References (10)
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2021-21284
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2021-21284
- WEBhttps://docs.docker.com/engine/release-notes/#20103
- WEBhttps://github.com/moby/moby/commit/64bd4485b3a66a597c02c95f5776395e540b2c7c
- WEBhttps://github.com/moby/moby/releases/tag/v19.03.15
- WEBhttps://github.com/moby/moby/releases/tag/v20.10.3
- WEBhttps://github.com/moby/moby/security/advisories/GHSA-7452-xqpj-6rpc
- WEBhttps://security.gentoo.org/glsa/202107-23
- WEBhttps://security.netapp.com/advisory/ntap-20210226-0005
- WEBhttps://www.debian.org/security/2021/dsa-4865