CVE intelligence and bounded remediation

CVE-2023-34091 — Kyverno is a policy engine designed for Kubernetes

Medium CVSS 6.5

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.

Severity
Medium
CVSS
6.5 (3.1)
Published
2023-06-01
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-285

Affected products

  • nirmata / kyverno

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

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Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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