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gh-159428: Don't read mimetypes.knownfiles by default on Windows #159445

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gh-159428: Don't read mimetypes.knownfiles by default on Windows #159445

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f3b14c4
Don't read mimetypes.knownfiles by default on Windows
cjames23 Oct 15, 2026
a987824
Update Lib/mimetypes.py
cjames23 Oct 15, 2026
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30 changes: 19 additions & 11 deletions Lib/mimetypes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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:
Expand All @@ -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
Expand Down
7 changes: 7 additions & 0 deletions Lib/test/test_mimetypes.py
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Expand Up @@ -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('')
Expand Down Expand Up @@ -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):
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Security/2026-10-15-03-47-08.gh-issue-159428.XHRKwY.rst
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Original file line number Diff line number Diff line change
@@ -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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