kyverno vulnerabilities and threats

Kyverno versions before 1.19.2 have an authorization bypass vulnerability that allows namespaced tenants to create resources of any kind in any namespace by manipulating generate rule templates. This can lead to attackers creating policies that cause the privileged background-controller to write sensitive resources such as NetworkPolicies or RoleBindings into namespaces they should not control, including kube-system. The vulnerability is fixed in version 1.19.2.

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 from 1.11.0 before 1.19.2 contains an unbounded decompression vulnerability in FetchSignatureBlob that allows attackers to exhaust memory by supplying highly compressed notary signature layers. Attackers who control registry referrers or signatures can publish small gzip layers that decompress beyond maxPayloadSize, causing admission controller OOM kills and denial of service.

Kyverno from 1.11.0 before 1.19.2 contains an unbounded decompression vulnerability in extractStatement that allows remote attackers to exhaust memory by supplying highly compressed attestation layers. Attackers controlling registry referrer artifacts can push gzip predicate layers exceeding maxPayloadSize when decompressed, causing admission controller OOM kills and denial of service.

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 before 1.19.2 contains a missing authorization vulnerability that allows namespaced Policy authors to read resources in other namespaces by templating generate.clone or cloneList namespace values. Attackers can annotate a triggering ConfigMap so the background-controller copies a victim namespace's sensitive ConfigMap into the attacker's namespace, enabling cross-tenant data disclosure.

Kyverno before 1.19.2 contains a denial-of-service vulnerability in the In and NotIn operators that allows attackers to crash the policy engine via an unchecked type assertion. Attackers can submit resources whose JMESPath-evaluated values yield arrays of integers, booleans, or mixed types, triggering a panic that disrupts admission control and policy enforcement.

Kyverno before 1.19.2 contains an authentication bypass in matchCertificateData that skips verifyImages subject and subjectRegExp checks when the signing certificate has no Subject Alternative Name. Attackers holding a leaf certificate from a configured private trust root can omit the SAN, set the expected Fulcio issuer OID, and sign malicious images that are admitted despite signer pinning.

Kyverno from 1.17.0 before 1.19.2 contains a missing authorization vulnerability in the mutate-existing background processor that allows namespaced tenants to modify resources outside their namespace. Attackers can create a NamespacedMutatingPolicy targeting Namespace objects or victim-namespace resources via CEL expressions, making the background-controller ServiceAccount strip Pod Security labels cluster-wide.

Kyverno before 1.19.2 contains an unchecked type assertion in buildStatementMap that allows unauthenticated attackers to crash the policy engine via crafted attestation statements. Attackers can push an OCI referrer manifest with a non-string type field to bypass image verification under failurePolicy Ignore or crash-loop the reports-controller.

Kyverno before 1.19.2 contains an unchecked type assertion in its variable-substitution engine that allows users who can submit resources to crash the policy engine. Attackers can submit resources with non-string fields referenced by {{- variable }} shallow substitution in policies, causing a panic that yields webhook denial of service and policy bypass under failurePolicy Ignore.

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 1.19.1 before 1.19.2 contains a namespace isolation bypass in APICall Fetch() in pkg/engine/apicall/apiCall.go because path.Clean treats '?' as a path character, letting the namespace regex match segments inside the query string. Users who can create namespaced policies can supply a URLPath like /api/v1/nodes?x=/namespaces/default/ that passes validation while client-go requests the cluster-scoped endpoint, reading resources outside their namespace.

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 before 1.19.2 contains a denial of service vulnerability that allows namespace-scoped policy authors to exhaust CPU and memory by submitting CEL expressions evaluated without runtime cost limits. Attackers can create a NamespacedValidatingPolicy or NamespacedDeletingPolicy with nested map comprehensions over large ConfigMap fields to OOM-kill Kyverno pods and block cluster-wide admission.

Kyverno before 1.19.2 contains an authorization bypass vulnerability in the Generation Handler that allows users with create/update permissions to trigger synchronized generate policies by spoofing internal generate.kyverno.io labels. Attackers can label a ConfigMap as managed-by kyverno with crafted policy, rule, and trigger labels to clone sensitive Secrets from restricted namespaces into their own namespace.

Kyverno before 1.19.2 contains a policy bypass vulnerability in the admissionpolicygenerator controller, which folds PolicyExceptions into generated ValidatingAdmissionPolicies while ignoring the --enablePolicyException, --exceptionNamespace, and policy kind gates. Users with namespaced create rights on PolicyExceptions can inject negated matchConditions into the generated policies to admit violating resources, bypassing cluster-wide enforcement.

Kyverno before 1.19.2 contains a denial of service vulnerability that allows namespaced policy authors to exhaust admission controller CPU by submitting pathological wildcard patterns. Attackers can create a Policy with crafted match and exclude names evaluated by ValidateMatchExcludeConflict, pinning cores and causing cluster-wide webhook timeouts that block resource operations.

Kyverno before 1.19.2 contains a denial of service vulnerability in substituteVariablesIfAny that allows low-privileged users to hang the admission webhook via self-referential variable templates. Attackers can create resources whose annotations re-introduce the embedded policy variable, causing unbounded substitution loops that exhaust CPU and memory and block cluster-wide admission.