Authentication bypass in Kubernetes

1) Improper Authentication

EUVDB-ID: #VU56243

Risk: Low

CVSSv3.1: 4 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-3636

CWE-ID: CWE-287 - Improper Authentication

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to the generated certificate for the in-cluster Service CA, incorrectly included additional certificates. The Service CA is automatically mounted into all pods, allowing them to safely connect to trusted in-cluster services that present certificates signed by the trusted Service CA. The incorrect inclusion of additional CAs in this certificate would allow an attacker that compromises any of the additional CAs to masquerade as a trusted in-cluster service.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Kubernetes: 1.21.0 - 1.21.1

External links

http://bugzilla.redhat.com/show_bug.cgi?id=1978621

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.