diff --git a/backport-CVE-2025-8291.patch b/backport-CVE-2025-8291.patch
new file mode 100644
index 0000000000000000000000000000000000000000..188c4136066f6e1da106db50e33a84fcb77799db
--- /dev/null
+++ b/backport-CVE-2025-8291.patch
@@ -0,0 +1,307 @@
+From 1e1d79a9de506ceb3dabb1ba9114c7ddb555253e Mon Sep 17 00:00:00 2001
+From: Serhiy Storchaka <storchaka@gmail.com>
+Date: Tue, 7 Oct 2025 20:55:44 +0300
+Subject: [PATCH] [3.13] gh-139700: Check consistency of the zip64 end of
+ central directory record (GH-139702) (GH-139708) (cherry picked from commit
+ 333d4a6f4967d3ace91492a39ededbcf3faa76a6)
+
+Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
+Support records with "zip64 extensible data" if there are no bytes
+prepended to the ZIP file.
+(cherry picked from commit 162997bb70e067668c039700141770687bc8f267)
+---
+ Lib/test/test_zipfile.py                      | 82 ++++++++++++++++++-
+ Lib/zipfile.py                                | 51 +++++++-----
+ ...-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
+
+diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
+index 52831a7bd7ce00..a0bca62ab88ac3 100644
+--- a/Lib/test/test_zipfile.py
++++ b/Lib/test/test_zipfile.py
+@@ -887,6 +887,8 @@ def make_zip64_file(
+         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.
+ 
+@@ -940,6 +942,12 @@ def make_zip64_file(
+ 
+         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))
+@@ -968,14 +976,17 @@ def make_zip64_file(
+             + 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"
+@@ -1006,6 +1017,7 @@ def test_bad_zip64_extra(self):
+         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.
+@@ -1017,6 +1029,7 @@ def test_bad_zip64_extra(self):
+         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.
+@@ -1026,6 +1039,7 @@ def test_bad_zip64_extra(self):
+         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
+@@ -1040,6 +1054,7 @@ def test_bad_zip64_extra(self):
+         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
+@@ -1052,6 +1067,7 @@ def test_bad_zip64_extra(self):
+         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
+@@ -1064,6 +1080,7 @@ def test_bad_zip64_extra(self):
+         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
+@@ -1075,6 +1092,63 @@ def test_bad_zip64_extra(self):
+         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.
+diff --git a/Lib/zipfile.py b/Lib/zipfile.py
+index 6a4cf7a972bf62..64289ebd674659 100644
+--- a/Lib/zipfile.py
++++ b/Lib/zipfile.py
+@@ -236,7 +236,7 @@ def is_zipfile(filename):
+         else:
+             with open(filename, "rb") as fp:
+                 result = _check_zipfile(fp)
+-    except OSError:
++    except (OSError, BadZipFile):
+         pass
+     return result
+ 
+@@ -244,16 +244,15 @@ def _EndRecData64(fpin, offset, endrec):
+     """
+     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
+@@ -261,16 +260,33 @@ def _EndRecData64(fpin, offset, endrec):
+     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
+@@ -280,6 +296,7 @@ def _EndRecData64(fpin, offset, endrec):
+     endrec[_ECD_ENTRIES_TOTAL] = dircount2
+     endrec[_ECD_SIZE] = dirsize
+     endrec[_ECD_OFFSET] = diroffset
++    endrec[_ECD_LOCATION] = offset - extrasz
+     return endrec
+ 
+ 
+@@ -313,7 +330,7 @@ def _EndRecData(fpin):
+         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"
+@@ -337,8 +354,7 @@ def _EndRecData(fpin):
+         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
+@@ -1386,9 +1402,6 @@ def _RealGetContents(self):
+ 
+         # "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 self.debug > 2:
+             inferred = concat + offset_cd
+@@ -1989,7 +2002,7 @@ def _write_end_record(self):
+                                    " 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)
+ 
+diff --git a/Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst b/Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst
+new file mode 100644
+index 00000000000000..a8e7a1f1878c6b
+--- /dev/null
++++ b/Misc/NEWS.d/next/Security/2025-10-07-19-31-34.gh-issue-139700.vNHU1O.rst
+@@ -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.
diff --git a/python3.spec b/python3.spec
index 8f98fc863d2391d17a29e727b041a2afa663927a..d9f41d84aa753bc59b902e21d21cf83ae817fe89 100644
--- a/python3.spec
+++ b/python3.spec
@@ -3,7 +3,7 @@ Summary: Interpreter of the Python3 programming language
 URL: https://www.python.org/
 
 Version: 3.11.6
-Release: 15
+Release: 16
 License: Python-2.0
 
 %global branchversion 3.11
@@ -113,6 +113,7 @@ Patch6017:  backport-CVE-2025-8194.patch
 Patch6018:  backport-CVE-2025-1795.patch
 Patch6019:  backport-CVE-2025-4516.patch
 Patch6020:  backport-CVE-2025-6069.patch
+Patch6021:  backport-CVE-2025-8291.patch
 
 Patch9000:  add-the-sm3-method-for-obtaining-the-salt-value.patch
 Patch9001:  0001-add-loongarch64-support-for-python.patch
@@ -872,6 +873,9 @@ export BEP_GTDLIST="$BEP_GTDLIST_TMP"
 %{_mandir}/*/*
 
 %changelog
+* Wed Oct 8 2025 lizhipeng <lizhipeng@kylinos.cn> - 3.11.6-16
+- fix CVE-2025-8291
+
 * Sat Sep 20 2025 xinsheng <xinsheng3@h-partners.com> - 3.11.6-15
 - Type:CVE
 - CVE:CVE-2025-6069