I think there's a "t" missing:Lib/zipimport.py609-610-                try:611:                    _boostrap_external._validate_hash_pyc(612-                        data, source_hash, fullname, exc_details)613-                except ImportError:614-                    return None615-    else:616-        source_mtime, source_size = \617-            _get_mtime_and_size_of_source(self, fullpath)618-619-        if source_mtime:

Good catch!  Would you like to submit a pull request to fix it?  Ideally such a PR should also include a test to exercise this code.

Is it possible to scan stdlib to find similar bugs?

A possible test case to trigger this code path based on testUncheckedHashBasedPyc would be as below. check_hash_based_pycs can be patched to be "always" so that the hash is validated using _bootstrap_external._validate_hash_pyc. The difference between "state = old" for pyc and "state = new" in py would ensure the hashes are different to raise ImportError expected and the test picks up state = new as the updated source code. Without fixing the typo trying to make hash validation would throw NameError.@unittest.mock.patch('_imp.check_hash_based_pycs', 'always')def test_checked_hash_based_change_pyc(self):    source = b"state = 'old'"    source_hash = importlib.util.source_hash(source)    bytecode = importlib._bootstrap_external._code_to_hash_pyc(        compile(source, "???", "exec"),        source_hash,        False,    )    files = {TESTMOD + ".py": (NOW, "state = 'new'"),             TESTMOD + ".pyc": (NOW - 20, bytecode)}    def check(mod):        self.assertEqual(mod.state, 'new')    self.doTest(None, files, TESTMOD, call=check)

Also since the fix involves modifying zipimport.py it would also require running "make regen-importlib && make -s" for changes to ensure the updated regen code is used.

Ma Lin, Running pylint/flake8 could possibly detect it but needs to be manually checked.issue36948 was a similar report I filed in the past using flake8 regarding NameError.pylint -Lib/zipimport.py:611:20: E0602: Undefined variable '_boostrap_external' (undefined-variable)flake8 -Lib/zipimport.py:611:21: F821 undefined name '_boostrap_external'

Wince you has virtually written a patch, do you mind to create a PR Karthikeyan?

Sure Serhiy, I will create one.

New changeset79f02fee1a542c440fd906fd54154c73fc0f8235 by Nick Coghlan (Xtreak) in branch 'master':bpo-39033: Fix NameError in zipimport during hash validation (GH-17588)https://github.com/python/cpython/commit/79f02fee1a542c440fd906fd54154c73fc0f8235

New changeset9955f33cdbf27de270038dfbad37d15b160ecca2 by Miss Islington (bot) (Karthikeyan Singaravelan) in branch '3.8':[3.8]bpo-39033: Fix NameError in zipimport during hash validation (GH-17588) (GH-17642)https://github.com/python/cpython/commit/9955f33cdbf27de270038dfbad37d15b160ecca2

Thank you, Mihail and Karthikeyan!