diff --git a/lib/modules/manager/kustomize/extract.spec.ts b/lib/modules/manager/kustomize/extract.spec.ts
index 10da86921eaf00df7d67c45cc6e1e7ce12f4beb2..e41d7719b874a1d8401033a858b2f7aa98329c00 100644
--- a/lib/modules/manager/kustomize/extract.spec.ts
+++ b/lib/modules/manager/kustomize/extract.spec.ts
@@ -186,6 +186,15 @@ describe('modules/manager/kustomize/extract', () => {
       expect(pkg).toBeNull();
     });
 
+    it('should return null on invalid input', () => {
+      const pkg = extractImage({
+        // @ts-expect-error: for testing
+        name: 3,
+        newTag: '',
+      });
+      expect(pkg).toBeNull();
+    });
+
     it('should correctly extract a default image', () => {
       const sample = {
         currentDigest: undefined,
diff --git a/lib/modules/manager/kustomize/extract.ts b/lib/modules/manager/kustomize/extract.ts
index 8c7e85f4dced64f5ebe1f8ab8021d0fe4380a7e8..5bccc523a5b34b3fa7a5e80b497e983f7b724c9b 100644
--- a/lib/modules/manager/kustomize/extract.ts
+++ b/lib/modules/manager/kustomize/extract.ts
@@ -67,7 +67,12 @@ export function extractImage(image: Image): PackageDependency | null {
   if (!image.name) {
     return null;
   }
-  const nameDep = splitImageParts(image.newName ?? image.name);
+  const nameToSplit = image.newName ?? image.name;
+  if (!is.string(nameToSplit)) {
+    logger.debug({ image }, 'Invalid image name');
+    return null;
+  }
+  const nameDep = splitImageParts(nameToSplit);
   const { depName } = nameDep;
   const { digest, newTag } = image;
   if (digest && newTag) {