diff --git a/cmd/kubeadm/app/phases/copycerts/main_test.go b/cmd/kubeadm/app/phases/copycerts/main_test.go
index 3e163f7403b..b49f13b9943 100644
--- a/cmd/kubeadm/app/phases/copycerts/main_test.go
+++ b/cmd/kubeadm/app/phases/copycerts/main_test.go
@@ -23,5 +23,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
+	// see: https://github.com/kubernetes/kubernetes/issues/104265
+	setNoUmask()
 	pkiutiltesting.RunWithPrivateKeyFixtureDirectory(m)
 }
diff --git a/cmd/kubeadm/app/phases/copycerts/testutil_umask.go b/cmd/kubeadm/app/phases/copycerts/testutil_umask.go
new file mode 100644
index 00000000000..e6ae29870c4
--- /dev/null
+++ b/cmd/kubeadm/app/phases/copycerts/testutil_umask.go
@@ -0,0 +1,27 @@
+// +build darwin linux
+
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package copycerts
+
+import "golang.org/x/sys/unix"
+
+// on unix where umask may be in effect, clear umask so tests
+// are not sensitive to the developer's system umask
+func setNoUmask() {
+	unix.Umask(0)
+}
diff --git a/cmd/kubeadm/app/phases/copycerts/testutil_umask_noop.go b/cmd/kubeadm/app/phases/copycerts/testutil_umask_noop.go
new file mode 100644
index 00000000000..11d9b1a2b7f
--- /dev/null
+++ b/cmd/kubeadm/app/phases/copycerts/testutil_umask_noop.go
@@ -0,0 +1,23 @@
+// +build !darwin,!linux
+
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package copycerts
+
+func setNoUmask() {
+	// no-op on not-unix
+}