Kyverno is a policy engine designed for Kubernetes. A security vulnerability was found in Kyverno where an attacker could cause denial of service of Kyverno. The vulnerable component in Kyvernos Notary verifier. An attacker would need control over the registry from which Kyverno would fetch attestations. With such a position, the attacker could return a malicious response to Kyverno, when Kyverno would send a request to the registry. The malicious response would cause denial of service of Kyverno, such that other users admission requests would be blocked from being processed. This is a vulnerability in a new component released in v1.11.0. The only users affected by this are those that have been building Kyverno from source at the main branch which is not encouraged. Users consuming official Kyverno releases are not affected. There are no known cases of this vulnerability being exploited in the wild.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Kyverno | Nirmata | 1.11.0 (including) | 1.11.0 (including) |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.