diff --git a/chrome/browser/storage_access_api/storage_access_grant_permission_context.cc b/chrome/browser/storage_access_api/storage_access_grant_permission_context.cc
index 3f31f0d867412..0c73297c9fc5f 100644
--- a/chrome/browser/storage_access_api/storage_access_grant_permission_context.cc
+++ b/chrome/browser/storage_access_api/storage_access_grant_permission_context.cc
@@ -563,6 +563,18 @@ StorageAccessGrantPermissionContext::GetContentSettingStatusInternal(
     return CONTENT_SETTING_ALLOW;
   }
 
+  // A nonce-partitioned (credentialless) frame must never inherit a
+  // pre-existing STORAGE_ACCESS grant: the HostContentSettingsMap lookup keys
+  // only on (requesting_origin, embedding_origin) and is unaware of the
+  // per-Page nonce. Returning ASK here forces requests through
+  // DecidePermission(), where the compromised-renderer gate runs and the
+  // renderer is killed via mojo::ReportBadMessage.
+  if (render_frame_host &&
+      (render_frame_host->IsCredentialless() ||
+       render_frame_host->GetStorageKey().ForbidsUnpartitionedStorageAccess())) {
+    return CONTENT_SETTING_ASK;
+  }
+
   ContentSetting setting = permissions::ContentSettingPermissionContextBase::
       GetContentSettingStatusInternal(render_frame_host, requesting_origin,
                                       embedding_origin);