https://github.com/python/cpython/commit/04a29bf8f9ff8526cd96cb7368400173303a390a
commit: 04a29bf8f9ff8526cd96cb7368400173303a390a
branch: main
author: Cary Hawkins <[email protected]>
committer: zooba <[email protected]>
date: 2026-10-15T22:03:28+01:00
summary:
gh-159428: Don't read mimetypes.knownfiles by default on Windows (GH-159445)
Make knownfiles empty on Windows so that only the registry is used by default.
Files passed to init() or assigned to knownfiles explicitly are still read.
files:
A Misc/NEWS.d/next/Security/2026-10-15-03-47-08.gh-issue-159428.XHRKwY.rst
M Lib/mimetypes.py
M Lib/test/test_mimetypes.py
diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 1d6b33fe854c943..561b99a92c8d16b 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -23,6 +23,8 @@
read_mime_types(file) -- parse one file, return a dictionary or None
"""
+import sys
+
try:
from _winapi import _mimetypes_read_windows_registry
except ImportError:
@@ -40,17 +42,23 @@
"suffix_map", "encodings_map", "types_map", "common_types"
]
-knownfiles = [
- "/etc/mime.types",
- "/etc/httpd/mime.types", # Mac OS X
- "/etc/httpd/conf/mime.types", # Apache
- "/etc/apache/mime.types", # Apache 1
- "/etc/apache2/mime.types", # Apache 2
- "/usr/local/etc/httpd/conf/mime.types",
- "/usr/local/lib/netscape/mime.types",
- "/usr/local/etc/httpd/conf/mime.types", # Apache 1.2
- "/usr/local/etc/mime.types", # Apache 1.3
- ]
+if sys.platform == "win32":
+ # The default paths would resolve to the root of the current drive on
Windows
+ # (e.g. C:\etc\mime.types), which unprivileged users can usually create.
+ # Only the registry is used by default.
+ knownfiles = []
+else:
+ knownfiles = [
+ "/etc/mime.types",
+ "/etc/httpd/mime.types", # Mac OS X
+ "/etc/httpd/conf/mime.types", # Apache
+ "/etc/apache/mime.types", # Apache 1
+ "/etc/apache2/mime.types", # Apache 2
+ "/usr/local/etc/httpd/conf/mime.types",
+ "/usr/local/lib/netscape/mime.types",
+ "/usr/local/etc/httpd/conf/mime.types", # Apache 1.2
+ "/usr/local/etc/mime.types", # Apache 1.3
+ ]
inited = False
_db = None
diff --git a/Lib/test/test_mimetypes.py b/Lib/test/test_mimetypes.py
index 1e0f6664af0d066..8e39552dba8aa89 100644
--- a/Lib/test/test_mimetypes.py
+++ b/Lib/test/test_mimetypes.py
@@ -271,6 +271,10 @@ def test_init_knownfiles(self):
mimetypes.init()
self.assertEqual(guess_file_type("file.test2")[0], "testing/test2")
+ @unittest.skipIf(sys.platform == "win32", "non-Windows only")
+ def test_default_knownfiles(self):
+ self.assertIn("/etc/mime.types", knownfiles)
+
def test_added_types_are_used(self):
mimetypes.add_type('testing/default-type', '')
mime_type, _ = mimetypes.guess_type('')
@@ -555,6 +559,9 @@ def test_registry_parsing(self):
eq(self.db.guess_type("image.jpg"), ("image/jpeg", None))
eq(self.db.guess_type("image.png"), ("image/png", None))
+ def test_default_knownfiles(self):
+ self.assertEqual(knownfiles, [])
+
@unittest.skipIf(not hasattr(_winapi, "_mimetypes_read_windows_registry"),
"read_windows_registry accelerator unavailable")
def test_registry_accelerator(self):
diff --git
a/Misc/NEWS.d/next/Security/2026-10-15-03-47-08.gh-issue-159428.XHRKwY.rst
b/Misc/NEWS.d/next/Security/2026-10-15-03-47-08.gh-issue-159428.XHRKwY.rst
new file mode 100644
index 000000000000000..d481ed2b74a20ea
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-10-15-03-47-08.gh-issue-159428.XHRKwY.rst
@@ -0,0 +1,2 @@
+:mod:`mimetypes` no longer reads the files listed in
:data:`mimetypes.knownfiles`
+by default on Windows, and uses only the registry.
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