CVE-2026-122307
Description
A flaw was found in Kyverno. This vulnerability allows an authenticated attacker with permissions to create policy exceptions to bypass cluster-wide security controls. The admission policy generator improperly folds policy exceptions into generated admission policies without enforcing configured exception gates and namespace boundaries. As a result, an attacker can admit non-compliant or violating resources into the Kubernetes cluster.
Statement
This vulnerability is rated with an Important severity because authenticated users possessing localized namespace privileges can circumvent cluster-wide admission controls, breaking security isolation boundaries to admit unauthorized workloads. Red Hat OpenShift does not package or distribute Kyverno, relying instead on built-in admission controllers and Security Context Constraints to enforce cluster security. Consequently, default Red Hat platforms are not impacted by this issue unless third-party Kyverno controllers are manually deployed.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
--- CME Mitigation Guidance (2026-11-06) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to enforce policy exception gates, namespace boundaries, and policy kind constraints within the admission policy generator before folding exceptions into ValidatingAdmissionPolicies: upgrade to Kyverno 1.19.2 (or the corresponding fixed Red Hat builds), which enforce --enablePolicyException, --exceptionNamespace boundaries, and policy kind constraints when folding PolicyExceptions into generated ValidatingAdmissionPolicies, closing all 2 injection vectors (crafted PolicyException creation in a non-permitted namespace, injection of negated matchConditions into generated ValidatingAdmissionPolicies). Until patched, this is a concern on Kubernetes clusters running Kyverno admissionpolicygenerator where users have namespaced PolicyException create permissions, so restrict RBAC permissions for creating PolicyException custom resources and audit API server requests for unauthorized exception creation. As a compensating measure, configure Kubernetes API server audit logging to detect creation of PolicyException custom resources and admission of violating workloads, enforce Pod Security Standards in Restricted mode via Pod Security Admission to block privileged workload execution independently, and use an independent admission controller to reject creation of PolicyException resources in unauthorized namespaces or targeting forbidden policies. These controls limit blast radius and contain exploitation, but they do not fix the underlying improper policy exception handling defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-706 Pod Security Standards (Restricted) (medium)
Understanding the Weakness (CWE)
Confidentiality,Access Control,Availability
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity; Varies by Context
When security decisions such as authentication and authorization are made based on the values of these inputs, attackers can bypass the security of the product to access whatever is being protected. An attacker could change these inputs using customized clients or other attacks. This change might not be detected. The consequences will depend on the associated functionality, but they can range from granting additional privileges to untrusted users to bypassing important security checks. Ultimately, this weakness may lead to exposure or modification of sensitive data, system crash, or execution of arbitrary code.
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