#VU54339 Protection Mechanism Failure in Kubernetes - CVE-2021-25736

Vulnerability identifier: #VU54339

Vulnerability risk: Medium

CVSSv4.0: 1.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-25736

CWE-ID: CWE-693

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Kubernetes
Server applications / Frameworks for developing and running applications

Vendor: Kubernetes

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to insufficient implementation of security measures in the Windows kube-proxy component. In a cloud environment that does not set the “.status.loadBalancer.ingress.ip” field in the LoadBalancer service status configuration (for example in AWS) the packets can be misrouted and reach an unintended destination. An attacker can bypass implemented security restrictions and perform MitM attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Kubernetes: 1.18.0 - 1.19.9, 1.20.0 - 1.20.5

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External links
https://access.redhat.com/errata/RHSA-2021:2130

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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 Internet.

Is there known malware, which exploits this vulnerability?

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