CVE-2023-34091

Kyverno before 1.19.2 contains an authorization bypass vulnerability that allows namespaced tenants to generate any resource kind in any namespace by templating the generate rule's kind and namespace with variables. Attackers can create a Policy and trigger ConfigMap in their own namespace, causing the privileged background-controller to write NetworkPolicies or RoleBindings into victim or kube-system namespaces.

Kyverno from 1.19.1 before 1.19.2 contains an authorization bypass vulnerability in the apiCall namespace clamp that allows namespace tenants to issue cross-namespace and cluster-scoped API requests by appending malformed percent-escapes to urlPath. Attackers can create namespaced Policies whose apiCall runs as the admission-controller ServiceAccount to read other namespaces' resources and create mutating webhooks, escalating to cluster admin.

Kyverno 1.18.0 before 1.19.2 contains a signature verification bypass in verifyImages because cached verification results are keyed by the image reference string (such as a tag) rather than bound to the verified digest, so cache hits skip signature and attestation checks. An attacker who can submit workloads and move a registry tag can warm the cache with a signed image, repoint the tag, and have Kyverno admit the workload and use mutateDigest to pin the unverified digest.

Kyverno from 1.17.0 before 1.19.2 contains a privilege escalation vulnerability that allows namespace-scoped tenants to modify resources in other namespaces through NamespacedMutatingPolicy targetMatchConstraints.expression CEL output lacking namespace checks. Attackers can emit a literal target such as another tenant's RoleBinding, which the cluster-wide background controller then mutates to add attacker subjects or alter Roles, NetworkPolicies, and ConfigMaps.

Kyverno from 1.16.0 before 1.19.2 fails to validate path segments in the resource argument of resource.get() and resource.post(), allowing namespaced CEL policies to escape their namespace. Tenants who can create a NamespacedValidatingPolicy can insert .. segments to read and write arbitrary cluster objects using the admission controller's ServiceAccount, leading to cluster takeover.

Kyverno from 1.19.1 before 1.19.2 validates a Policy's context.apiCall urlPath after cleaning it but executes the raw path, whose fragment or query the Kubernetes client discards. A namespace-scoped user who can create a Policy can hide ../ segments behind # or ? to reach cluster-scoped endpoints with Kyverno's ServiceAccount, gaining cluster admin.

Kyverno from 1.17.0 before 1.19.2 contains an authorization bypass vulnerability that allows namespace admins to escape namespace confinement because the cleanup controller builds its context loader with a nil policy. Attackers can create a namespaced CleanupPolicy with apiCall or globalReference context entries to read cross-namespace Secrets and modify validatingwebhookconfigurations using the cleanup controller's ServiceAccount.

Kyverno from 1.17.0 before 1.19.2 contains an authorization bypass vulnerability that allows namespace tenants to overwrite resources in other namespaces via NamespacedMutatingPolicy mutate-existing targetMatchConstraints.expression. Attackers can return a CEL map literal fabricating a target with an attacker-chosen metadata.namespace, causing the privileged background controller to overwrite Secrets, Deployments, or policies cluster-wide.

Kyverno before 1.19.2 contains a privilege escalation vulnerability that allows namespace admins to create resources beyond their RBAC because generate-rule admission checks verify the controller's permissions, not the author's. Attackers can create a namespaced Policy with generate rules targeting other namespaces or cluster-scoped kinds, making the background controller create or clone resources cluster-wide.

Kyverno before 1.19.1 fails to properly validate URL-encoded path segments in Policy apiCall urlPath, allowing namespace tenants to bypass the per-namespace clamp and create objects in other namespaces as the admission-controller ServiceAccount. Attackers can exploit this by using percent-encoded directory traversal sequences to create MutatingWebhookConfiguration objects cluster-wide or PolicyException objects in the kyverno namespace, enabling privilege escalation to cluster admin.