diff --git a/changelog/fragments/csv-whdescs-defaults.yaml b/changelog/fragments/csv-whdescs-defaults.yaml
new file mode 100644
index 00000000000..5d3cffc2095
--- /dev/null
+++ b/changelog/fragments/csv-whdescs-defaults.yaml
@@ -0,0 +1,7 @@
+entries:
+  - description: >
+      Default a CSV's `spec.webhookDefinition[].admissionReviewVersions` to "v1beta1".
+    kind: addition
+  - description: >
+      Default a CSV's `spec.webhookDefinition[].sideEffects` to "None".
+    kind: addition
diff --git a/internal/generate/clusterserviceversion/clusterserviceversion_updaters.go b/internal/generate/clusterserviceversion/clusterserviceversion_updaters.go
index 9e1a1a61e48..a8fc1992b9b 100644
--- a/internal/generate/clusterserviceversion/clusterserviceversion_updaters.go
+++ b/internal/generate/clusterserviceversion/clusterserviceversion_updaters.go
@@ -290,6 +290,9 @@ func applyWebhooks(c *collector.Manifests, csv *operatorsv1alpha1.ClusterService
 	csv.Spec.WebhookDefinitions = webhookDescriptions
 }
 
+// The default AdmissionReviewVersions set in a CSV if not set in the source webhook.
+var defaultAdmissionReviewVersions = []string{"v1beta1"}
+
 // validatingToWebhookDescription transforms webhook into a WebhookDescription.
 func validatingToWebhookDescription(webhook admissionregv1.ValidatingWebhook, depName string) operatorsv1alpha1.WebhookDescription {
 	description := operatorsv1alpha1.WebhookDescription{
@@ -303,6 +306,13 @@ func validatingToWebhookDescription(webhook admissionregv1.ValidatingWebhook, de
 		TimeoutSeconds:          webhook.TimeoutSeconds,
 		AdmissionReviewVersions: webhook.AdmissionReviewVersions,
 	}
+	if len(description.AdmissionReviewVersions) == 0 {
+		description.AdmissionReviewVersions = defaultAdmissionReviewVersions
+	}
+	if description.SideEffects == nil {
+		seNone := admissionregv1.SideEffectClassNone
+		description.SideEffects = &seNone
+	}
 
 	if serviceRef := webhook.ClientConfig.Service; serviceRef != nil {
 		if serviceRef.Port != nil {
@@ -331,6 +341,13 @@ func mutatingToWebhookDescription(webhook admissionregv1.MutatingWebhook, depNam
 		AdmissionReviewVersions: webhook.AdmissionReviewVersions,
 		ReinvocationPolicy:      webhook.ReinvocationPolicy,
 	}
+	if len(description.AdmissionReviewVersions) == 0 {
+		description.AdmissionReviewVersions = defaultAdmissionReviewVersions
+	}
+	if description.SideEffects == nil {
+		seNone := admissionregv1.SideEffectClassNone
+		description.SideEffects = &seNone
+	}
 
 	if serviceRef := webhook.ClientConfig.Service; serviceRef != nil {
 		if serviceRef.Port != nil {
diff --git a/internal/generate/testdata/clusterserviceversions/output/memcached-operator.clusterserviceversion.yaml b/internal/generate/testdata/clusterserviceversions/output/memcached-operator.clusterserviceversion.yaml
index f4fb80f3f8c..fc8cd8a179a 100644
--- a/internal/generate/testdata/clusterserviceversions/output/memcached-operator.clusterserviceversion.yaml
+++ b/internal/generate/testdata/clusterserviceversions/output/memcached-operator.clusterserviceversion.yaml
@@ -184,7 +184,8 @@ spec:
     url: https://your.domain
   version: 0.0.1
   webhookdefinitions:
-  - admissionReviewVersions: null
+  - admissionReviewVersions:
+    - v1beta1
     deploymentName: memcached-operator-controller-manager
     failurePolicy: Fail
     generateName: vmemcached.kb.io
@@ -198,10 +199,11 @@ spec:
       - UPDATE
       resources:
       - memcacheds
-    sideEffects: null
+    sideEffects: None
     type: ValidatingAdmissionWebhook
     webhookPath: /validate-cache-my-domain-v1alpha1-memcached
-  - admissionReviewVersions: null
+  - admissionReviewVersions:
+    - v1beta1
     deploymentName: memcached-operator-controller-manager
     failurePolicy: Fail
     generateName: mmemcached.kb.io
@@ -215,6 +217,6 @@ spec:
       - UPDATE
       resources:
       - memcacheds
-    sideEffects: null
+    sideEffects: None
     type: MutatingAdmissionWebhook
     webhookPath: /mutate-cache-my-domain-v1alpha1-memcached