diff --git a/news/1634.bugfix b/news/1634.bugfix
new file mode 100644
index 0000000000..b0d7788b80
--- /dev/null
+++ b/news/1634.bugfix
@@ -0,0 +1,2 @@
+Do not expose private metadata via relationfield serializer.
+[maethu]
diff --git a/src/plone/restapi/serializer/relationfield.py b/src/plone/restapi/serializer/relationfield.py
index 28483ce424..c54145f1eb 100644
--- a/src/plone/restapi/serializer/relationfield.py
+++ b/src/plone/restapi/serializer/relationfield.py
@@ -1,3 +1,4 @@
+from plone import api
 from plone.dexterity.interfaces import IDexterityContent
 from plone.restapi.interfaces import IFieldSerializer
 from plone.restapi.interfaces import IJsonCompatible
@@ -17,7 +18,8 @@
 @adapter(IRelationValue)
 @implementer(IJsonCompatible)
 def relationvalue_converter(value):
-    if value.to_object:
+    mtool = api.portal.get_tool("portal_membership")
+    if value.to_object and mtool.checkPermission("View", value.to_object):
         request = getRequest()
         request.form["metadata_fields"] = ["UID"]
         summary = getMultiAdapter((value.to_object, request), ISerializeToJsonSummary)()
@@ -33,4 +35,9 @@ class RelationChoiceFieldSerializer(DefaultFieldSerializer):
 @adapter(IRelationList, IDexterityContent, Interface)
 @implementer(IFieldSerializer)
 class RelationListFieldSerializer(DefaultFieldSerializer):
-    pass
+    def __call__(self):
+        value = self.get_value()
+        if value:
+            return [item for item in json_compatible(value) if item]
+        else:
+            return super().__call__()
diff --git a/src/plone/restapi/tests/test_content_get.py b/src/plone/restapi/tests/test_content_get.py
index 34cd70d137..fa0e3171fe 100644
--- a/src/plone/restapi/tests/test_content_get.py
+++ b/src/plone/restapi/tests/test_content_get.py
@@ -18,7 +18,6 @@
 
 
 class TestContentGet(unittest.TestCase):
-
     layer = PLONE_RESTAPI_DX_FUNCTIONAL_TESTING
 
     def setUp(self):
@@ -137,6 +136,31 @@ def test_get_content_includes_related_items(self):
             response.json()["relatedItems"],
         )
 
+    def test_get_content_includes_related_items_filtered_by_view_permission(self):
+        intids = getUtility(IIntIds)
+        self.portal.folder1.doc1.relatedItems = [
+            RelationValue(intids.getId(self.portal.folder1.folder2.doc2)),
+        ]
+
+        # Remove view permission
+        self.portal.folder1.folder2.doc2.manage_permission(
+            "View", roles=[], acquire=False
+        )
+        self.portal.folder1.folder2.doc2.reindexObjectSecurity()
+        transaction.commit()
+
+        response = requests.get(
+            self.portal.folder1.doc1.absolute_url(),
+            headers={"Accept": "application/json"},
+            auth=(SITE_OWNER_NAME, SITE_OWNER_PASSWORD),
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(0, len(response.json()["relatedItems"]))
+        self.assertEqual(
+            [],
+            response.json()["relatedItems"],
+        )
+
     def test_get_content_related_items_without_workflow(self):
         intids = getUtility(IIntIds)