https://github.com/python/cpython/commit/35dd324f6e30735162a68cde84bb04a169004325
commit: 35dd324f6e30735162a68cde84bb04a169004325
branch: 3.11
author: Cary Hawkins <[email protected]>
committer: pablogsal <[email protected]>
date: 2026-10-25T12:37:12-07:00
summary:
[3.11] gh-159428: Don't read mimetypes.knownfiles by default on Windows
(GH-159445) (#159573)
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.
(cherry picked from commit 04a29bf8f9ff8526cd96cb7368400173303a390a)
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 4a6b00b216b634..d610483738ec85 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -45,17 +45,23 @@
"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 cc91d539d477fa..2b531615c40ee0 100644
--- a/Lib/test/test_mimetypes.py
+++ b/Lib/test/test_mimetypes.py
@@ -51,6 +51,10 @@ def test_default_data(self):
eq(self.db.guess_type("foo.tar.bz2"), ("application/x-tar", "bzip2"))
eq(self.db.guess_type("foo.tar.xz"), ("application/x-tar", "xz"))
+ @unittest.skipIf(sys.platform == "win32", "non-Windows only")
+ def test_default_knownfiles(self):
+ self.assertIn("/etc/mime.types", knownfiles)
+
def test_data_urls(self):
eq = self.assertEqual
guess_type = self.db.guess_type
@@ -288,6 +292,9 @@ 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 00000000000000..d481ed2b74a20e
--- /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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