CVEs-PoC/2021/CVE-2021-21284.md

### [CVE-2021-21284](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21284)
![](https://img.shields.io/static/v1?label=Product&message=moby&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-22%20Improper%20Limitation%20of%20a%20Pathname%20to%20a%20Restricted%20Directory%20('Path%20Traversal')&color=brighgreen)

### 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.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/ARPSyndicate/cvemon
- https://github.com/adavarski/HomeLab-Proxmox-k8s-DevSecOps-playground
- https://github.com/adavarski/HomeLab-k8s-DevSecOps-playground
- https://github.com/fenixsecurelabs/core-nexus
- https://github.com/phoenixvlabs/core-nexus
- https://github.com/phxvlabsio/core-nexus