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2.7.18.16: mimetypes reads C:\etc\mime.types etc. on Windows (CVE-2024-3220) #98

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Merged
icanhasmath merged 1 commit into from
Oct 28, 2026
Merged

2.7.18.16: mimetypes reads C:\etc\mime.types etc. on Windows (CVE-2024-3220) #98

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28 changes: 17 additions & 11 deletions Lib/mimetypes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,17 +37,23 @@
"add_type","read_mime_types","init"
]

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
13 changes: 13 additions & 0 deletions Lib/test/test_mimetypes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@
from test import test_support

# Tell it we don't know about external files:
# The default list, before it is emptied below for test isolation.
knownfiles = mimetypes.knownfiles
mimetypes.knownfiles = []
mimetypes.inited = False
mimetypes._default_mime_types()
Expand Down Expand Up @@ -67,6 +69,12 @@ def test_guess_all_types(self):
eq(all, [])


class KnownfilesTestCase(unittest.TestCase):
@unittest.skipIf(sys.platform == "win32", "non-Windows only")
def test_default_knownfiles(self):
self.assertIn("/etc/mime.types", knownfiles)


@unittest.skipUnless(sys.platform.startswith("win"), "Windows only")
class Win32MimeTypesTestCase(unittest.TestCase):
def setUp(self):
Expand All @@ -90,6 +98,10 @@ def test_registry_parsing(self):
eq(db.guess_type("image.jpg"), ("image/jpeg", None))
eq(db.guess_type("image.png"), ("image/png", None))

def test_default_knownfiles(self):
# CVE-2024-3220: the Unix paths would resolve to e.g. C:\etc\mime.types
self.assertEqual(knownfiles, [])

def test_non_latin_extension(self):
import _winreg

Expand Down Expand Up @@ -163,6 +175,7 @@ def __getattr__(self, name):

def test_main():
test_support.run_unittest(MimeTypesTestCase,
KnownfilesTestCase,
Win32MimeTypesTestCase
)

Expand Down