privilege escalation in Moby
Key facts
- Attack vector
- Adjacent network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Partial Red Hat: 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| moby | moby | before 19.03.15; 20.0.0 to before 20.10.3 | 19.03.15, 20.10.3 | Patch available | CNA |
| — | github.com/moby/moby (Go) | before 19.3.15 | 19.3.15 | Patch available | GHSA-7452-xqpj-6rpc |
| — | github.com/moby/moby (Go) | 20.10.0-beta1 to before 20.10.3 | 20.10.3 | Patch available | GHSA-7452-xqpj-6rpc |
- moby Vendormoby Affected before 19.03.15; 20.0.0 to before 20.10.3 Fixed in 19.03.15, 20.10.3 Patch available CNA
- github.com/moby/moby (Go) Vendor— Affected before 19.3.15 Fixed in 19.3.15 Patch available GHSA-7452-xqpj-6rpc
- github.com/moby/moby (Go) Vendor— Affected 20.10.0-beta1 to before 20.10.3 Fixed in 20.10.3 Patch available GHSA-7452-xqpj-6rpc
CPE configurations NVD · 3
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:docker:docker:*:*:*:*:*:*:*:* | before 19.03.15; 20.0.0 to before 20.10.3 | Vulnerable | Docker |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:a:netapp:e-series_santricity_os_controller:*:*:*:*:*:*:*:* | 11.0.0 – 11.60.3 | Vulnerable | NetApp |
- cpe:2.3:a:docker:docker:*:*:*:*:*:*:*:* Versions before 19.03.15; 20.0.0 to before 20.10.3 Vulnerable ·Docker
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:a:netapp:e-series_santricity_os_controller:*:*:*:*:*:*:*:* Versions 11.0.0 – 11.60.3 Vulnerable ·NetApp
Remediation
- Fix · CNA moby (moby) Fixed in 19.03.15, 20.10.3
- Fix · GHSA-7452-xqpj-6rpc github.com/moby/moby (Go) Fixed in 19.3.15 Advisory →
- Fix · GHSA-7452-xqpj-6rpc github.com/moby/moby (Go) Fixed in 20.10.3 Advisory →
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
moby — GLSA-202107-23
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2021-04385 Docker daemon crash during image pull of malicious imagePriority LOW 35
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
Timeline
- 2026-10-02 Threatist record created from CVE-2021-21284
- 2026-10-03 Alias added: GHSA-7452-xqpj-6rpc
References
Advisory 7
- https://docs.docker.com/engine/release-notes/#20103
- https://github.com/moby/moby/releases/tag/v20.10.3
- https://github.com/moby/moby/releases/tag/v19.03.15
- https://github.com/moby/moby/security/advisories/GHSA-7452-xqpj-6rpc
- https://security.netapp.com/advisory/ntap-20210226-0005/
- DSA-4865
- https://nvd.nist.gov/vuln/detail/CVE-2021-21284
More moby vulnerabilities
- TI-2026-14229 Tar extraction in moby/go-archive can write outside the destination directory via link following CVSS 4.0HIGH 7.1
- TI-2021-12512 Moby HyperKit uninitialized memory use in virtio-sock pci_vtsock_proc_tx CVSS 3.1HIGH 7.1
- TI-2024-27462 Moby authz zero length regression CVSS 3.1CRITICAL 10.0
- TI-2024-15672 BuildKit interactive containers API does not validate entitlements check CVSS 3.1CRITICAL 9.8
- TI-2024-15671 BuildKit possible host system access from mount stub cleaner CVSS 3.1CRITICAL 10.0
- TI-2026-26365 Moby: AuthZ plugin bypass with oversized request body CVSS 3.1HIGH 8.8
Sources
- CVE-2021-21284 · CVE Program
- CVE-2021-21284 · NVD
- FIRST EPSS
- GHSA-7452-xqpj-6rpc · GitHub Advisory Database · CC BY 4.0
- CVE-2021-21284 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences