#VU50273 Permissions, Privileges, and Access Controls in Docker - CVE-2021-21284

Vulnerability identifier: #VU50273

Vulnerability risk: Medium

CVSSv4.0: 6.1 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-21284

CWE-ID: CWE-264

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Docker
Server applications / Virtualization software

Vendor: Docker Inc.

Description

The vulnerability allows a remote attacker to escalate privileges on the system.

The vulnerability exists due to application does not properly impose security restrictions when using the --userns-remap option. A remote authenticated attacker on the local network can send a specially crafted request and gain elevated privileges as root on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Docker: before 19.03.15

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External links
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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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.