File CVE-2025-8291-consistency-zip64.patch of Package python314
From 5454f861e2b3c96fa1e6430dc952544670955f69 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Tue, 7 Oct 2025 20:15:26 +0300
Subject: [PATCH] gh-139700: Check consistency of the zip64 end of central
directory record (GH-139702)
Support records with "zip64 extensible data" if there are no bytes
prepended to the ZIP file.
(cherry picked from commit 162997bb70e067668c039700141770687bc8f267)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
---
Lib/test/test_zipfile/test_core.py | 82 +++++++++-
Lib/zipfile/__init__.py | 51 +++---
Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst | 3
3 files changed, 113 insertions(+), 23 deletions(-)
create mode 100644 Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst
Index: Python-3.14.0/Lib/test/test_zipfile/test_core.py
===================================================================
--- Python-3.14.0.orig/Lib/test/test_zipfile/test_core.py 2025-11-12 01:03:54.947094045 +0100
+++ Python-3.14.0/Lib/test/test_zipfile/test_core.py 2025-11-12 01:04:11.766432381 +0100
@@ -898,6 +898,8 @@
self, file_size_64_set=False, file_size_extra=False,
compress_size_64_set=False, compress_size_extra=False,
header_offset_64_set=False, header_offset_extra=False,
+ extensible_data=b'',
+ end_of_central_dir_size=None, offset_to_end_of_central_dir=None,
):
"""Generate bytes sequence for a zip with (incomplete) zip64 data.
@@ -951,6 +953,12 @@
central_dir_size = struct.pack('<Q', 58 + 8 * len(central_zip64_fields))
offset_to_central_dir = struct.pack('<Q', 50 + 8 * len(local_zip64_fields))
+ if end_of_central_dir_size is None:
+ end_of_central_dir_size = 44 + len(extensible_data)
+ if offset_to_end_of_central_dir is None:
+ offset_to_end_of_central_dir = (108
+ + 8 * len(local_zip64_fields)
+ + 8 * len(central_zip64_fields))
local_extra_length = struct.pack("<H", 4 + 8 * len(local_zip64_fields))
central_extra_length = struct.pack("<H", 4 + 8 * len(central_zip64_fields))
@@ -979,14 +987,17 @@
+ filename
+ central_extra
# Zip64 end of central directory
- + b"PK\x06\x06,\x00\x00\x00\x00\x00\x00\x00-\x00-"
- + b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00"
+ + b"PK\x06\x06"
+ + struct.pack('<Q', end_of_central_dir_size)
+ + b"-\x00-\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00"
+ b"\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00"
+ central_dir_size
+ offset_to_central_dir
+ + extensible_data
# Zip64 end of central directory locator
- + b"PK\x06\x07\x00\x00\x00\x00l\x00\x00\x00\x00\x00\x00\x00\x01"
- + b"\x00\x00\x00"
+ + b"PK\x06\x07\x00\x00\x00\x00"
+ + struct.pack('<Q', offset_to_end_of_central_dir)
+ + b"\x01\x00\x00\x00"
# end of central directory
+ b"PK\x05\x06\x00\x00\x00\x00\x01\x00\x01\x00:\x00\x00\x002\x00"
+ b"\x00\x00\x00\x00"
@@ -1017,6 +1028,7 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_file_size_extra))
self.assertIn('file size', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_file_size_extra)))
# zip64 file size present, zip64 compress size present, one field in
# extra, expecting two, equals missing compress size.
@@ -1028,6 +1040,7 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_compress_size_extra))
self.assertIn('compress size', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_compress_size_extra)))
# zip64 compress size present, no fields in extra, expecting one,
# equals missing compress size.
@@ -1037,6 +1050,7 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_compress_size_extra))
self.assertIn('compress size', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_compress_size_extra)))
# zip64 file size present, zip64 compress size present, zip64 header
# offset present, two fields in extra, expecting three, equals missing
@@ -1051,6 +1065,7 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_header_offset_extra))
self.assertIn('header offset', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_header_offset_extra)))
# zip64 compress size present, zip64 header offset present, one field
# in extra, expecting two, equals missing header offset
@@ -1063,6 +1078,7 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_header_offset_extra))
self.assertIn('header offset', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_header_offset_extra)))
# zip64 file size present, zip64 header offset present, one field in
# extra, expecting two, equals missing header offset
@@ -1075,6 +1091,7 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_header_offset_extra))
self.assertIn('header offset', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_header_offset_extra)))
# zip64 header offset present, no fields in extra, expecting one,
# equals missing header offset
@@ -1086,6 +1103,63 @@
with self.assertRaises(zipfile.BadZipFile) as e:
zipfile.ZipFile(io.BytesIO(missing_header_offset_extra))
self.assertIn('header offset', str(e.exception).lower())
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(missing_header_offset_extra)))
+
+ def test_bad_zip64_end_of_central_dir(self):
+ zipdata = self.make_zip64_file(end_of_central_dir_size=0)
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'Corrupt.*record'):
+ zipfile.ZipFile(io.BytesIO(zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ zipdata = self.make_zip64_file(end_of_central_dir_size=100)
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'Corrupt.*record'):
+ zipfile.ZipFile(io.BytesIO(zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ zipdata = self.make_zip64_file(offset_to_end_of_central_dir=0)
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'Corrupt.*record'):
+ zipfile.ZipFile(io.BytesIO(zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ zipdata = self.make_zip64_file(offset_to_end_of_central_dir=1000)
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'Corrupt.*locator'):
+ zipfile.ZipFile(io.BytesIO(zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ def test_zip64_end_of_central_dir_record_not_found(self):
+ zipdata = self.make_zip64_file()
+ zipdata = zipdata.replace(b"PK\x06\x06", b'\x00'*4)
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'record not found'):
+ zipfile.ZipFile(io.BytesIO(zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ zipdata = self.make_zip64_file(
+ extensible_data=b'\xca\xfe\x04\x00\x00\x00data')
+ zipdata = zipdata.replace(b"PK\x06\x06", b'\x00'*4)
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'record not found'):
+ zipfile.ZipFile(io.BytesIO(zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ def test_zip64_extensible_data(self):
+ # These values are what is set in the make_zip64_file method.
+ expected_file_size = 8
+ expected_compress_size = 8
+ expected_header_offset = 0
+ expected_content = b"test1234"
+
+ zipdata = self.make_zip64_file(
+ extensible_data=b'\xca\xfe\x04\x00\x00\x00data')
+ with zipfile.ZipFile(io.BytesIO(zipdata)) as zf:
+ zinfo = zf.infolist()[0]
+ self.assertEqual(zinfo.file_size, expected_file_size)
+ self.assertEqual(zinfo.compress_size, expected_compress_size)
+ self.assertEqual(zinfo.header_offset, expected_header_offset)
+ self.assertEqual(zf.read(zinfo), expected_content)
+ self.assertTrue(zipfile.is_zipfile(io.BytesIO(zipdata)))
+
+ with self.assertRaisesRegex(zipfile.BadZipFile, 'record not found'):
+ zipfile.ZipFile(io.BytesIO(b'prepended' + zipdata))
+ self.assertFalse(zipfile.is_zipfile(io.BytesIO(b'prepended' + zipdata)))
def test_generated_valid_zip64_extra(self):
# These values are what is set in the make_zip64_file method.
Index: Python-3.14.0/Lib/zipfile/__init__.py
===================================================================
--- Python-3.14.0.orig/Lib/zipfile/__init__.py 2025-11-12 01:03:55.239347604 +0100
+++ Python-3.14.0/Lib/zipfile/__init__.py 2025-11-12 01:04:11.767105446 +0100
@@ -265,7 +265,7 @@
else:
with open(filename, "rb") as fp:
result = _check_zipfile(fp)
- except OSError:
+ except (OSError, BadZipFile):
pass
return result
@@ -275,9 +275,6 @@
# "concat" is zero, unless zip was concatenated to another file
concat = endrec[_ECD_LOCATION] - size_cd - offset_cd
- if endrec[_ECD_SIGNATURE] == stringEndArchive64:
- # If Zip64 extension structures are present, account for them
- concat -= (sizeEndCentDir64 + sizeEndCentDir64Locator)
if debug > 2:
inferred = concat + offset_cd
@@ -289,16 +286,15 @@
"""
Read the ZIP64 end-of-archive records and use that to update endrec
"""
- try:
- fpin.seek(offset - sizeEndCentDir64Locator, 2)
- except OSError:
- # If the seek fails, the file is not large enough to contain a ZIP64
+ offset -= sizeEndCentDir64Locator
+ if offset < 0:
+ # The file is not large enough to contain a ZIP64
# end-of-archive record, so just return the end record we were given.
return endrec
-
+ fpin.seek(offset)
data = fpin.read(sizeEndCentDir64Locator)
if len(data) != sizeEndCentDir64Locator:
- return endrec
+ raise OSError("Unknown I/O error")
sig, diskno, reloff, disks = struct.unpack(structEndArchive64Locator, data)
if sig != stringEndArchive64Locator:
return endrec
@@ -306,16 +302,33 @@
if diskno != 0 or disks > 1:
raise BadZipFile("zipfiles that span multiple disks are not supported")
- # Assume no 'zip64 extensible data'
- fpin.seek(offset - sizeEndCentDir64Locator - sizeEndCentDir64, 2)
+ offset -= sizeEndCentDir64
+ if reloff > offset:
+ raise BadZipFile("Corrupt zip64 end of central directory locator")
+ # First, check the assumption that there is no prepended data.
+ fpin.seek(reloff)
+ extrasz = offset - reloff
data = fpin.read(sizeEndCentDir64)
if len(data) != sizeEndCentDir64:
- return endrec
+ raise OSError("Unknown I/O error")
+ if not data.startswith(stringEndArchive64) and reloff != offset:
+ # Since we already have seen the Zip64 EOCD Locator, it's
+ # possible we got here because there is prepended data.
+ # Assume no 'zip64 extensible data'
+ fpin.seek(offset)
+ extrasz = 0
+ data = fpin.read(sizeEndCentDir64)
+ if len(data) != sizeEndCentDir64:
+ raise OSError("Unknown I/O error")
+ if not data.startswith(stringEndArchive64):
+ raise BadZipFile("Zip64 end of central directory record not found")
+
sig, sz, create_version, read_version, disk_num, disk_dir, \
dircount, dircount2, dirsize, diroffset = \
struct.unpack(structEndArchive64, data)
- if sig != stringEndArchive64:
- return endrec
+ if (diroffset + dirsize != reloff or
+ sz + 12 != sizeEndCentDir64 + extrasz):
+ raise BadZipFile("Corrupt zip64 end of central directory record")
# Update the original endrec using data from the ZIP64 record
endrec[_ECD_SIGNATURE] = sig
@@ -325,6 +338,7 @@
endrec[_ECD_ENTRIES_TOTAL] = dircount2
endrec[_ECD_SIZE] = dirsize
endrec[_ECD_OFFSET] = diroffset
+ endrec[_ECD_LOCATION] = offset - extrasz
return endrec
@@ -358,7 +372,7 @@
endrec.append(filesize - sizeEndCentDir)
# Try to read the "Zip64 end of central directory" structure
- return _EndRecData64(fpin, -sizeEndCentDir, endrec)
+ return _EndRecData64(fpin, filesize - sizeEndCentDir, endrec)
# Either this is not a ZIP file, or it is a ZIP file with an archive
# comment. Search the end of the file for the "end of central directory"
@@ -382,8 +396,7 @@
endrec.append(maxCommentStart + start)
# Try to read the "Zip64 end of central directory" structure
- return _EndRecData64(fpin, maxCommentStart + start - filesize,
- endrec)
+ return _EndRecData64(fpin, maxCommentStart + start, endrec)
# Unable to find a valid end of central directory structure
return None
@@ -2142,7 +2155,7 @@
" would require ZIP64 extensions")
zip64endrec = struct.pack(
structEndArchive64, stringEndArchive64,
- 44, 45, 45, 0, 0, centDirCount, centDirCount,
+ sizeEndCentDir64 - 12, 45, 45, 0, 0, centDirCount, centDirCount,
centDirSize, centDirOffset)
self.fp.write(zip64endrec)
Index: Python-3.14.0/Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ Python-3.14.0/Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst 2025-11-12 01:04:11.767493557 +0100
@@ -0,0 +1,3 @@
+Check consistency of the zip64 end of central directory record. Support
+records with "zip64 extensible data" if there are no bytes prepended to the
+ZIP file.
