PID  ELAPSED %CPU STAT COMMAND

def ask_yes_no(question, default=False) -> bool:
    while True:
        try:
            ...
            c = input().lower()
            ...
        except EOFError:
            stdout.write("\nPlease respond with yes/y or no/n\n")
        except KeyboardInterrupt:
            return False
        
When stdin isn't a TTY (exactly the case for vbash -c "..." run non-interactively, as in the repro), input() raises EOFError immediately and repeatedly — there's nothing to wait on, so the loop spins as fast as the CPU allows, burning ~100% of a core forever.
        
commit_confirm() (config_mgmt.py:222) calls ask_yes_no(prompt_str, default=True) whenever no_prompt isn't set, which is exactly what the reported vbash one-liner hits. This also explains the "after successful confirm" framing: a later confirm call only stops the systemd timer and pkills the notify script — it never touches the original
commit_confirm process, which is stuck in the EOFError loop from the very first prompt and was never actually confirmed. It just keeps spinning, orphaned, while the system otherwise continues to work normally — hence unnoticed until something checks CPU/thermal load.

Suggested minimal fix — bail out to default immediately when stdin isn't a TTY, instead of ever entering the retry loop: 

def ask_yes_no(question, default=False) -> bool:
    from sys import stdin, stdout
    if not stdin.isatty():
        return default
    default_msg = "[Y/n]" if default else "[y/N]"
    while True:
        ...
    
This is behaviorally identical to a user pressing Enter (accepting the default) in an interactive session, so it changes nothing for normal interactive use. ask_yes_no() has ~40 call sites across the tree (image_installer, pki, format_disk, remote, etc.) that would all hang the same way if invoked non-interactively today — this fix resolves
the underlying issue for all of them, not just commit-confirm.

Happy to open a PR with this + a unit test (mocking stdin.isatty()) if useful, @jestabro — let me know if you'd rather take it from here since it's already assigned to you.

PID  ELAPSED %CPU STAT COMMAND

index 77e30cbb0..13ef8709a 100644
--- a/python/vyos/utils/io.py
+++ b/python/vyos/utils/io.py
@@ -56,7 +56,10 @@ def ask_input(question, default='', numeric_only=False, valid_responses=[],

 def ask_yes_no(question, default=False) -> bool:
     """Ask a yes/no question via input() and return their answer."""
-    from sys import stdout
+    from sys import stdin, stdout
+
+    if not stdin.isatty():
+        return default
     default_msg = "[Y/n]" if default else "[y/N]"
     while True:
         try:
diff --git a/src/tests/test_utils_io.py b/src/tests/test_utils_io.py
new file mode 100644
index 000000000..7adb0dc61
--- /dev/null 
+++ b/src/tests/test_utils_io.py
@@ -0,0 +1,46 @@
+# Copyright VyOS maintainers and contributors <maintainers@vyos.io>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import unittest
+from unittest.mock import patch
+
+from vyos.utils.io import ask_yes_no
+
+
+class TestVyOSUtilsIO(unittest.TestCase):
+    def test_ask_yes_no_non_interactive_returns_default_without_reading_stdin(self):
+        # T9185: on a non-TTY stdin (e.g. a non-interactive vbash session),
+        # input() raises EOFError immediately and forever; ask_yes_no() must
+        # return the default straight away instead of ever looping on input().
+        with patch('sys.stdin') as mock_stdin:
+            mock_stdin.isatty.return_value = False
+            with patch('builtins.input') as mock_input:
+                self.assertTrue(ask_yes_no('Proceed?', default=True))
+                self.assertFalse(ask_yes_no('Proceed?', default=False))
+                mock_input.assert_not_called()
+
+    def test_ask_yes_no_interactive_reads_input(self):
+        with patch('sys.stdin') as mock_stdin:
+            mock_stdin.isatty.return_value = True
+            with patch('builtins.input', return_value='y'):
+                self.assertTrue(ask_yes_no('Proceed?', default=False))
+            with patch('builtins.input', return_value='n'):
+                self.assertFalse(ask_yes_no('Proceed?', default=True))
+            with patch('builtins.input', return_value=''):
+                self.assertTrue(ask_yes_no('Proceed?', default=True))
+                self.assertFalse(ask_yes_no('Proceed?', default=False))
+
+
+if __name__ == '__main__':
+    unittest.main()

Dazu als Begleittext, damit klar ist, dass es schon einen PR gibt:

▎ Opened a PR with this fix + the test above: https://github.com/vyos/vyos-1x/pull/5390