Summary A kyverno ClusterPolicy, ie. "disallow-privileged-containers," can be overridden by the creation of a PolicyException in a random namespace.

Details By design, PolicyExceptions are consumed from any namespace. Administrators may not recognize that this allows users with privileges to non-kyverno namespaces to create exceptions.

PoC 1. Administrator creates "disallow-privileged-containers" ClusterPolicy that applies to resources in the namespace "ubuntu-restricted" 2. Cluster user creates a PolicyException object for "disallow-privileged-containers" in namespace "ubuntu-restricted" 3. Cluster user creates a pod with a privileged container in "ubuntu-restricted" 4. Cluster user escalates to root on the node from the privileged container

Impact Administrators attempting to enforce cluster security through kyverno policies, but that allow less privileged users to create resources

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.

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.

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 vulnerability was in Kyvernos Notary verifier. An attacker would need control over the registry from which Kyverno would fetch signatures. 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.

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 vulnerability was in Kyvernos Notary verifier. An attacker would need control over the registry from which Kyverno would fetch signatures. 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.

Kyverno is a policy engine designed for Kubernetes. In versions of Kyverno prior to 1.10.0, resources which have the deletionTimestamp field defined can bypass validate, generate, or mutate-existing policies, even in cases where the validationFailureAction field is set to Enforce. This situation occurs as resources pending deletion were being consciously exempted by Kyverno, as a way to reduce processing load as policies are typically not applied to objects which are being deleted. However, this could potentially result in allowing a malicious user to leverage the Kubernetes finalizers feature by setting a finalizer which causes the Kubernetes API server to set the deletionTimestamp and then not completing the delete operation as a way to explicitly to bypass a Kyverno policy. Note that this is not applicable to Kubernetes Pods but, as an example, a Kubernetes Service resource can be manipulated using an indefinite finalizer to bypass policies. This is resolved in Kyverno 1.10.0. There is no known workaround.

Impact

Users of the podSecurity (validate.podSecurity) subrule in Kyverno versions v1.9.2 and v1.9.3 may be unable to enforce the check for the Seccomp control at the baseline level when using a version value of latest. There is no effect if a version number is referenced instead. See the documentation for information on this subrule type. Users of Kyverno v1.9.2 and v1.9.3 are affected.

Patches

v1.9.4 v1.10.0

Workarounds

To work around this issue without upgrading to v1.9.4, temporarily install individual policies for the respective Seccomp checks in baseline here and restricted here.

References

https://kyverno.io/docs/writing-policies/validate/#pod-security https://github.com/kyverno/kyverno/pull/7263