CVE-2023-34091: kyverno Improper Authorization

Vulnerability summary

CVE-2023-34091 is a medium (CVSS 6.5) Improper Authorization vulnerability in kyverno. EPSS estimates a 0.50% chance of exploitation in the next 30 days, higher than 41.3% of scored vulnerabilities.

Timeline

1. 01-06-2023
   PublishedVulnerability first disclosed.
2. 08-01-2025
   Last modifiedVulnerability information updated.

Description

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.

• CWE-285Improper AuthorizationThe product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.