Kubectl/API Server YAML parsing vulnerable to "Billion Laughs" Attack

Improper input validation in the Kubernetes API server in versions v1.0-1.12 and versions prior to v1.13.12, v1.14.8, v1.15.5, and v1.16.2 allows authorized users to send malicious YAML or JSON payloads, causing the API server to consume excessive CPU or memory, potentially crashing and becoming unavailable. Prior to v1.14.0, default RBAC policy authorized anonymous users to submit requests that could trigger this vulnerability. Clusters upgraded from a version prior to v1.14.0 keep the more permissive policy by default for backwards compatibility.

Recent assessments:

busterb at October 10, 2019 7:24pm UTC reported:

As I understand it, most kubernetes clusters will require auth or a foothold to reach in the first place. Why would you bother with a DoS attack at that point? Much more attacker value to be had in exploiting the cluster in ways that don’t bring it down.

Compare authenticated:
<https://www.shodan.io/search?query=kubernetes+401&gt;

And unauthenticated searches:
<https://www.shodan.io/search?query=kubernetes+!401&gt;

Assessed Attacker Value: 1
Assessed Attacker Value: 1Assessed Attacker Value: 1