.. date: 2026-03-10-09-46-44
.. gh-issue: 145731
.. nonce: 5uEGgb
.. release date: 2026-03-10
.. section: Windows

Fix negative timestamp during DST on Windows. Patch by Hugo van Kemenade.

..

.. date: 2026-02-27-10-57-20
.. gh-issue: 145307
.. nonce: ueoT7j
.. section: Windows

Defers loading of the ``psapi.dll`` module until it is used by
:func:`ctypes.util.dllist`.

..

.. date: 2026-02-13-11-07-51
.. gh-issue: 144551
.. nonce: ENtMYD
.. section: Windows

Updated bundled version of OpenSSL to 3.5.5.

..

.. date: 2026-03-04-17-39-15
.. gh-issue: 144741
.. nonce: 0RHhBF
.. section: Tests

Fix ``test_frame_pointer_unwind`` when Python is built with
:option:`--enable-shared`. Classify also libpython frames as ``"python"``.
Patch by Victor Stinner.

..

.. date: 2026-02-12-12-12-00
.. gh-issue: 144739
.. nonce: -fx1tN
.. section: Tests

When Python was compiled with system expat older then 2.7.2 but tests run
with newer expat, still skip
:class:`!test.test_pyexpat.MemoryProtectionTest`.

..

.. date: 2026-03-04-18-59-17
.. gh-issue: 145506
.. nonce: 6hwvEh
.. section: Security

Fixes :cve:`2026-2297` by ensuring that ``SourcelessFileLoader`` uses
:func:`io.open_code` when opening ``.pyc`` files.

..

.. date: 2026-01-31-21-56-54
.. gh-issue: 144370
.. nonce: fp9m8t
.. section: Security

Disallow usage of control characters in status in :mod:`wsgiref.handlers` to
prevent HTTP header injections. Patch by Benedikt Johannes.

..

.. date: 2026-03-07-15-00-00
.. gh-issue: 145623
.. nonce: 2Y7LzT
.. section: Library

Fix crash in :mod:`struct` when calling :func:`repr` or ``__sizeof__()`` on
an uninitialized :class:`struct.Struct` object created via
``Struct.__new__()`` without calling ``__init__()``.

..

.. date: 2026-03-05-19-01-28
.. gh-issue: 145551
.. nonce: gItPRl
.. section: Library

Fix InvalidStateError when cancelling process created by
:func:`asyncio.create_subprocess_exec` or
:func:`asyncio.create_subprocess_shell`. Patch by Daan De Meyer.

..

.. date: 2026-03-05-16-06-09
.. gh-issue: 141510
.. nonce: dFPAQS
.. section: Library

:mod:`marshal` now supports :class:`frozendict` objects. The marshal format
version was increased to 6. Patch by Victor Stinner.

..

.. date: 2026-03-03-11-49-44
.. gh-issue: 145417
.. nonce: m_HxIL
.. section: Library

:mod:`venv`: Prevent incorrect preservation of SELinux context when copying
the ``Activate.ps1`` script. The script inherited the SELinux security
context of the system template directory, rather than the destination
project directory.

..

.. date: 2026-03-02-20-08-09
.. gh-issue: 145335
.. nonce: lVTBvd
.. section: Library

``os.listdir(-1)`` and ``os.scandir(-1)`` now fail with
``OSError(errno.EBADF)`` rather than listing the current directory.
``os.listxattr(-1)`` now fails with ``OSError(errno.EBADF)`` rather than
listing extended attributes of the current directory. Patch by Victor
Stinner.

..

.. date: 2026-03-02-19-41-39
.. gh-issue: 145376
.. nonce: OOzSOh
.. section: Library

Fix double free and null pointer dereference in unusual error scenarios in
:mod:`hashlib` and :mod:`hmac` modules.

..

.. date: 2026-02-28-00-55-00
.. gh-issue: 145301
.. nonce: Lk2bRl
.. section: Library

:mod:`hmac`: fix a crash when the initialization of the underlying C
extension module fails.

..

.. date: 2026-02-27-19-00-26
.. gh-issue: 145301
.. nonce: 2Wih4b
.. section: Library

:mod:`hashlib`: fix a crash when the initialization of the underlying C
extension module fails.

..

.. date: 2026-02-27-18-04-51
.. gh-issue: 76007
.. nonce: 17idfK
.. section: Library

The ``version`` attribute of the :mod:`tarfile` module is deprecated and
slated for removal in Python 3.20.

..

.. date: 2026-02-23-20-52-55
.. gh-issue: 145158
.. nonce: vWJtxI
.. section: Library

Avoid undefined behaviour from signed integer overflow when parsing format
strings in the :mod:`struct` module.

..

.. date: 2026-02-21-17-34-53
.. gh-issue: 123853
.. nonce: 6RUwWh
.. section: Library

Removed Windows 95 compatibility for :func:`locale.getdefaultlocale`.

..

.. date: 2026-02-20-13-03-10
.. gh-issue: 66802
.. nonce: OYcAi_
.. section: Library

Add :func:`unicodedata.block` function to return the `Unicode block
<https://www.unicode.org/versions/Unicode17.0.0/core-spec/chapter-3/#G64189>`_
of a character.

..

.. date: 2026-02-19-20-54-25
.. gh-issue: 145033
.. nonce: X9EBPQ
.. section: Library

Add :data:`typing.TypeForm`, implementing :pep:`747`. Patch by Jelle
Zijlstra.

..

.. date: 2026-02-19-18-02-54
.. gh-issue: 141510
.. nonce: qzvYsO
.. section: Library

:func:`dataclasses.field`: if *metadata* is ``None``, use an empty
:class:`frozendict`, instead of a :func:`~types.MappingProxyType` of an
empty :class:`dict`. Patch by Victor Stinner.

..

.. date: 2026-02-19-17-50-47
.. gh-issue: 145006
.. nonce: 9gqA0Q
.. section: Library

Add :exc:`ModuleNotFoundError` hints when a module for a different ABI
exists.

..

.. date: 2026-02-19-16-26-08
.. gh-issue: 141510
.. nonce: 4Qxy8_
.. section: Library

``ParameterizedMIMEHeader.params`` of :mod:`email.headerregistry` is now a
:class:`frozendict` instead of a :class:`types.MappingProxyType`. Patch by
Victor Stinner.

..

.. date: 2026-02-19-15-42-06
.. gh-issue: 134872
.. nonce: sjYX1-
.. section: Library

Add valid import name suggestions on :exc:`ModuleNotFoundError`.

..

.. date: 2026-02-19-10-57-40
.. gh-issue: 88091
.. nonce: N7qGV-
.. section: Library

Fix :func:`unicodedata.decomposition` for Hangul characters.

..

.. date: 2026-02-19-00-00-00
.. gh-issue: 144986
.. nonce: atexit-leak
.. section: Library

Fix a memory leak in :func:`atexit.register`. Patch by Shamil Abdulaev.

..

.. date: 2026-02-18-13-45-00
.. gh-issue: 144777
.. nonce: R97q0a
.. section: Library

Fix data races in :class:`io.IncrementalNewlineDecoder` in the
:term:`free-threaded build`.

..

.. date: 2026-02-18-00-00-00
.. gh-issue: 144809
.. nonce: nYpEUx
.. section: Library

Make :class:`collections.deque` copy atomic in the :term:`free-threaded
build`.

..

.. date: 2026-02-17-11-28-37
.. gh-issue: 141510
.. nonce: OpAz0M
.. section: Library

The :mod:`copy` module now supports the :class:`frozendict` type. Patch by
Pieter Eendebak based on work by Victor Stinner.

..

.. date: 2026-02-17-11-15-17
.. gh-issue: 141510
.. nonce: ZmqEUb
.. section: Library

The :mod:`json` module now supports the :class:`frozendict` type. Patch by
Victor Stinner.

..

.. date: 2026-02-15-12-02-20
.. gh-issue: 144835
.. nonce: w_oS_J
.. section: Library

Added missing explanations for some parameters in :func:`glob.glob` and
:func:`glob.iglob`.

..

.. date: 2026-02-15-00-00-00
.. gh-issue: 144833
.. nonce: TUelo1
.. section: Library

Fixed a use-after-free in :mod:`ssl` when ``SSL_new()`` returns NULL in
``newPySSLSocket()``. The error was reported via a dangling pointer after
the object had already been freed.

..

.. date: 2026-02-14-14-56-44
.. gh-issue: 140715
.. nonce: AbSheM
.. section: Library

Add ``'%D'`` support to :meth:`~datetime.datetime.strptime`.

..

.. date: 2026-02-13-14-20-10
.. gh-issue: 144782
.. nonce: 0Y8TKj
.. section: Library

Fix :class:`argparse.ArgumentParser` to be :mod:`pickleable <pickle>`.

..

.. date: 2026-02-13-11-14-18
.. gh-issue: 144763
.. nonce: cDwnEE
.. section: Library

Fix a race condition in :mod:`tracemalloc`: it no longer detaches the
attached thread state to acquire its internal lock. Patch by Victor Stinner.

..

.. date: 2026-02-13-00-00-00
.. gh-issue: 142224
.. nonce: BidiMissing
.. section: Library

:func:`unicodedata.bidirectional` now return the correct default bidi class
for unassigned code points.

..

.. date: 2026-02-12-17-56-17
.. gh-issue: 117865
.. nonce: jE1ema
.. section: Library

Reduce the import time of :mod:`inspect` module by ~20%.

..

.. date: 2026-02-10-22-05-51
.. gh-issue: 144156
.. nonce: UbrC7F
.. section: Library

Fix the folding of headers by the :mod:`email` library when :rfc:`2047`
encoded words are used.  Now whitespace is correctly preserved and also
correctly added between adjacent encoded words.  The latter property was
broken by the fix for gh-92081, which mostly fixed previous failures to
preserve whitespace.

..

.. date: 2026-02-10-16-56-05
.. gh-issue: 66305
.. nonce: PZ6GN8
.. section: Library

Fixed a hang on Windows in the :mod:`tempfile` module when trying to create
a temporary file or subdirectory in a non-writable directory.

..

.. date: 2026-02-09-02-16-36
.. gh-issue: 144615
.. nonce: s04x4n
.. section: Library

Methods directly decorated with :deco:`functools.singledispatchmethod` now
dispatch on the second argument when called after being accessed as class
attributes. Patch by Bartosz Sławecki.

..

.. date: 2026-02-08-17-09-10
.. gh-issue: 144321
.. nonce: w58PhQ
.. section: Library

The functional syntax for creating :class:`typing.NamedTuple` classes now
supports passing any :term:`iterable` of fields and types. Previously, only
sequences were supported.

..

.. date: 2026-02-07-16-37-42
.. gh-issue: 144475
.. nonce: 8tFEXw
.. section: Library

Calling :func:`repr` on :func:`functools.partial` is now safer when the
partial object's internal attributes are replaced while the string
representation is being generated.

..

.. date: 2026-02-07-16-31-42
.. gh-issue: 144285
.. nonce: iyH9iL
.. section: Library

Attribute suggestions in :exc:`AttributeError` tracebacks are now formatted
differently to make them easier to understand, for example: ``Did you mean
'.datetime.now' instead of '.now'``. Contributed by Bartosz Sławecki.

..

.. date: 2026-02-03-19-57-41
.. gh-issue: 144316
.. nonce: wop870
.. section: Library

Fix crash in ``_remote_debugging`` that caused ``test_external_inspection``
to intermittently fail. Patch by Taegyun Kim.

..

.. date: 2026-01-17-08-44-25
.. gh-issue: 143637
.. nonce: qyPqDo
.. section: Library

Fixed a crash in socket.sendmsg() that could occur if ancillary data is
mutated re-entrantly during argument parsing.

..

.. date: 2026-01-12-19-39-57
.. gh-issue: 140652
.. nonce: HvM9Bl
.. section: Library

Fix a crash in :func:`!_interpchannels.list_all` after closing a channel.

..

.. date: 2026-01-11-18-35-52
.. gh-issue: 143698
.. nonce: gXDzsJ
.. section: Library

Allow *scheduler* and *setpgroup* arguments to be explicitly :const:`None`
when calling :func:`os.posix_spawn` or :func:`os.posix_spawnp`. Patch by
Bénédikt Tran.

..

.. date: 2026-01-11-16-59-22
.. gh-issue: 143698
.. nonce: b-Cpeb
.. section: Library

Raise :exc:`TypeError` instead of :exc:`SystemError` when the *scheduler* in
:func:`os.posix_spawn` or :func:`os.posix_spawnp` is not a tuple. Patch by
Bénédikt Tran.

..

.. date: 2026-01-11-13-03-32
.. gh-issue: 142516
.. nonce: u7An-s
.. section: Library

:mod:`ssl`: fix reference leaks in :class:`ssl.SSLContext` objects. Patch by
Bénédikt Tran.

..

.. date: 2026-01-10-22-58-30
.. gh-issue: 85809
.. nonce: 0eW4wt
.. section: Library

Added :term:`path-like object` support for :func:`shutil.make_archive`.

..

.. date: 2026-01-01-05-26-00
.. gh-issue: 143304
.. nonce: Kv7x9Q
.. section: Library

Fix :class:`ctypes.CDLL` to honor the ``handle`` parameter on POSIX systems.

..

.. date: 2025-12-18-00-14-16
.. gh-issue: 142781
.. nonce: gcOeYF
.. section: Library

:mod:`zoneinfo`: fix a crash when instantiating :class:`~zoneinfo.ZoneInfo`
objects for which the internal class-level cache is inconsistent.

..

.. date: 2025-12-16-13-34-48
.. gh-issue: 142787
.. nonce: wNitJX
.. section: Library

Fix assertion failure in :mod:`sqlite3` blob subscript when slicing with
indices that result in an empty slice.

..

.. date: 2025-12-06-16-14-18
.. gh-issue: 142352
.. nonce: pW5HLX88
.. section: Library

Fix :meth:`asyncio.StreamWriter.start_tls` to transfer buffered data from
:class:`~asyncio.StreamReader` to the SSL layer, preventing data loss when
upgrading a connection to TLS mid-stream (e.g., when implementing PROXY
protocol support).

..

.. date: 2025-10-10-14-08-58
.. gh-issue: 139899
.. nonce: 09leRY
.. section: Library

Introduced :meth:`importlib.abc.MetaPathFinder.discover` and
:meth:`importlib.abc.PathEntryFinder.discover` to allow module and submodule
name discovery without assuming the use of traditional filesystem based
imports.

..

.. date: 2025-08-04-23-20-43
.. gh-issue: 137335
.. nonce: IIjDJN
.. section: Library

Get rid of any possibility of a name conflict for named pipes in
:mod:`multiprocessing` and :mod:`asyncio` on Windows, no matter how small.

..

.. date: 2025-06-24-19-07-18
.. gh-issue: 135883
.. nonce: 38cePA
.. section: Library

Fix :mod:`sqlite3`'s :ref:`interactive shell <sqlite3-cli>` keeping part of
previous commands when scrolling history.

..

.. date: 2024-09-30-15-31-59
.. gh-issue: 124748
.. nonce: KYzYFp
.. section: Library

Improve :exc:`TypeError` error message when
:meth:`!weakref.WeakKeyDictionary.update` is used with keyword-only
parameters.

..

.. date: 2023-02-05-20-02-30
.. gh-issue: 80667
.. nonce: 7LmzeA
.. section: Library

Add support for Tangut Ideographs names in :mod:`unicodedata`.

..

.. bpo: 42353
.. date: 2022-02-05-00-15-03
.. nonce: 0ebVGG
.. section: Library

The :mod:`re` module gains a new :func:`re.prefixmatch` function as an
explicit spelling of what has to date always been known as :func:`re.match`.
:class:`re.Pattern` similary gains a :meth:`re.Pattern.prefixmatch` method.

Why? Explicit is better than implicit. Other widely used languages all use
the term "match" to mean what Python uses the term "search" for. The
unadorened "match" name in Python has been a frequent case of confusion and
coding bugs due to the inconsistency with the rest if the software industry.

We do not plan to deprecate and remove the older ``match`` name.

..

.. bpo: 40243
.. date: 2020-04-10-14-29-53
.. nonce: 85HRib
.. section: Library

Fix :meth:`!unicodedata.ucd_3_2_0.numeric` for non-decimal values.

..

.. bpo: 40212
.. date: 2020-04-07-05-09-34
.. nonce: oPYeBs
.. section: Library

Re-enable :func:`os.posix_fallocate` and :func:`os.posix_fadvise` on AIX.

..

.. bpo: 3405
.. date: 2018-05-11-12-26-16
.. nonce: CacMw9
.. section: Library

Add support for user data of Tk virtual events and detail for ``Enter``,
``Leave``, ``FocusIn``, ``FocusOut``, and ``ConfigureRequest`` events to
:mod:`tkinter`.

..

.. bpo: 32234
.. date: 2017-12-15-09-32-57
.. nonce: XaOkhR
.. section: Library

:class:`mailbox.Mailbox` instances can now be used as a context manager. The
Mailbox is locked on context entry and unlocked and closed at context exit.

..

.. date: 2026-03-03-08-18-00
.. gh-issue: 145450
.. nonce: VI7GXj
.. section: Documentation

Document missing public :class:`wave.Wave_write` getter methods.

..

.. date: 2026-01-06-16-04-08
.. gh-issue: 110937
.. nonce: SyO5lk
.. section: Documentation

Document rest of full public :class:`importlib.metadata.Distribution` API.
Also add the (already documented) :class:`~importlib.metadata.PackagePath`
to ``__all__``.

..

.. date: 2025-08-02-18-59-01
.. gh-issue: 136246
.. nonce: RIK7nE
.. section: Documentation

A new "Improve this page" link is available in the left-hand sidebar of the
docs, offering links to create GitHub issues, discussion forum posts, or
pull requests.

..

.. date: 2026-03-09-18-52-03
.. gh-issue: 145701
.. nonce: 79KQyO
.. section: Core and Builtins

Fix :exc:`SystemError` when ``__classdict__`` or
``__conditional_annotations__`` is in a class-scope inlined comprehension.
Found by OSS Fuzz in :oss-fuzz:`491105000`.

..

.. date: 2026-03-06-21-05-05
.. gh-issue: 145615
.. nonce: NKXXZgDW
.. section: Core and Builtins

Fixed a memory leak in the :term:`free-threaded build` where mimalloc pages
could become permanently unreclaimable until the owning thread exited.

..

.. date: 2026-03-06-01-36-20
.. gh-issue: 116738
.. nonce: OWVWRx
.. section: Core and Builtins

Make :meth:`!mmap.mmap.set_name` thread-safe on the :term:`free threaded
<free threading>` build.

..

.. date: 2026-03-05-19-10-56
.. gh-issue: 145566
.. nonce: H4RupyYN
.. section: Core and Builtins

In the free threading build, skip the stop-the-world pause when reassigning
``__class__`` on a newly created object.

..

.. date: 2026-03-05-16-16-17
.. gh-issue: 143055
.. nonce: qDUFlY
.. section: Core and Builtins

Fix crash in AST unparser when unparsing dict comprehension unpacking. Found
by OSS Fuzz in :oss-fuzz:`489790200`.

..

.. date: 2026-03-01-13-37-31
.. gh-issue: 145335
.. nonce: e36kPJ
.. section: Core and Builtins

Fix a crash in :func:`os.pathconf` when called with ``-1`` as the path
argument.

..

.. date: 2026-02-28-16-46-17
.. gh-issue: 145376
.. nonce: lG5u1a
.. section: Core and Builtins

Fix reference leaks in various unusual error scenarios.

..

.. date: 2026-02-26-21-36-00
.. gh-issue: 145234
.. nonce: w0mQ9n
.. section: Core and Builtins

Fixed a ``SystemError`` in the parser when an encoding cookie (for example,
UTF-7) decodes to carriage returns (``\r``). Newlines are now normalized
after decoding in the string tokenizer.

Patch by Pablo Galindo.

..

.. date: 2026-02-26-21-07-38
.. gh-issue: 145275
.. nonce: qE-3O1
.. section: Core and Builtins

Added the :option:`-X pathconfig_warnings<-X>` and
:envvar:`PYTHON_PATHCONFIG_WARNINGS` options, allowing to disable warnings
from :ref:`sys-path-init`.

..

.. date: 2026-02-26-20-51-54
.. gh-issue: 145273
.. nonce: B5QcUp
.. section: Core and Builtins

A warning is now shown during :ref:`sys-path-init` if it can't find a valid
standard library.

..

.. date: 2026-02-26-18-00-00
.. gh-issue: 145241
.. nonce: hL2k9Q
.. section: Core and Builtins

Specialized the parser error for when ``with`` items are followed by a
trailing comma (for example, ``with item,:``), raising a clearer
:exc:`SyntaxError` message. Patch by Pablo Galindo and Bartosz Sławecki.

..

.. date: 2026-02-26-12-00-00
.. gh-issue: 130555
.. nonce: TMSOIu
.. section: Core and Builtins

Fix use-after-free in :meth:`dict.clear` when the dictionary values are
embedded in an object and a destructor causes re-entrant mutation of the
dictionary.

..

.. date: 2026-02-25-15-02-08
.. gh-issue: 145197
.. nonce: G6hAUk
.. section: Core and Builtins

Fix JIT trace crash when recording function from cleared generator frame.

..

.. date: 2026-02-24-18-30-56
.. gh-issue: 145187
.. nonce: YjPu1Z
.. section: Core and Builtins

Fix compiler assertion fail when a type parameter bound contains an invalid
expression in a conditional block.

..

.. date: 2026-02-23-23-18-28
.. gh-issue: 145142
.. nonce: T-XbVe
.. section: Core and Builtins

Fix a crash in the free-threaded build when the dictionary argument to
:meth:`str.maketrans` is concurrently modified.

..

.. date: 2026-02-22-22-05-09
.. gh-issue: 145118
.. nonce: TaKMJE
.. section: Core and Builtins

:meth:`str.maketrans` now accepts :class:`frozendict`.

..

.. date: 2026-02-22-20-15-00
.. gh-issue: 144015
.. nonce: pystrhex_simd
.. section: Core and Builtins

Speed up :meth:`bytes.hex`, :meth:`bytearray.hex`, :func:`binascii.hexlify`,
and :mod:`hashlib` ``.hexdigest()`` operations with SIMD on x86-64, ARM64,
and ARM32 with NEON when built with gcc (version 12 or higher) or clang
(version 3 or higher) compilers.  Around 1.1-3x faster for common 16-64 byte
inputs such as hashlib hex digests, and up to 8x faster for larger data.

..

.. date: 2026-02-22-19-05-03
.. gh-issue: 145118
.. nonce: bU6Sic
.. section: Core and Builtins

:func:`type` now accepts :class:`frozendict` as an argument.

..

.. date: 2026-02-22-07-51-10
.. gh-issue: 145064
.. nonce: iIMGKA
.. section: Core and Builtins

Fix JIT optimizer assertion failure during ``CALL_ALLOC_AND_ENTER_INIT``
side exit.

..

.. date: 2026-02-21-12-16-46
.. gh-issue: 145055
.. nonce: VyT-zI
.. section: Core and Builtins

:func:`exec` and :func:`eval` now accept :class:`frozendict` for *globals*.
Patch by Victor Stinner.

..

.. date: 2026-02-21-09-47-45
.. gh-issue: 145058
.. nonce: e-RBw-
.. section: Core and Builtins

Fix a crash when :func:`!__lazy_import__` is passed a non-string argument,
by raising an :exc:`TypeError` instead.

..

.. date: 2026-02-19-12-49-15
.. gh-issue: 144995
.. nonce: Ob2oYJ
.. section: Core and Builtins

Optimize :class:`memoryview` comparison: a :class:`memoryview` is equal to
itself, there is no need to compare values. Patch by Victor Stinner.

..

.. date: 2026-02-18-21-44-39
.. gh-issue: 141510
.. nonce: 7LST2O
.. section: Core and Builtins

Update specializer to support frozendict. Patch by Donghee Na.

..

.. date: 2026-02-17-22-27-11
.. gh-issue: 141510
.. nonce: -4yYsf
.. section: Core and Builtins

Optimize :meth:`!frozendict.fromkeys` to avoid unnecessary thread-safety
operations in frozendict cases. Patch by Donghee Na.

..

.. date: 2026-02-17-21-04-03
.. gh-issue: 100239
.. nonce: LyVabQ
.. section: Core and Builtins

Speedup ``BINARY_OP_EXTEND`` for exact floats and medium-size integers by up
to 15%. Patch by Chris Eibl.

..

.. date: 2026-02-17-18-27-28
.. gh-issue: 144914
.. nonce: DcXO4m
.. section: Core and Builtins

Use ``mimalloc`` for raw memory allocations such as via
:c:func:`PyMem_RawMalloc` for better performance on :term:`free-threaded
builds <free-threaded build>`. Patch by Kumar Aditya.

..

.. date: 2026-02-16-12-28-43
.. gh-issue: 144872
.. nonce: k9_Q30
.. section: Core and Builtins

Fix heap buffer overflow in the parser found by OSS-Fuzz.

..

.. date: 2026-02-13-18-30-59
.. gh-issue: 144766
.. nonce: JGu3x3
.. section: Core and Builtins

Fix a crash in fork child process when perf support is enabled.

..

.. date: 2026-02-13-12-00-00
.. gh-issue: 144759
.. nonce: d3qYpe
.. section: Core and Builtins

Fix undefined behavior in the lexer when ``start`` and ``multi_line_start``
pointers are ``NULL`` in ``_PyLexer_remember_fstring_buffers()`` and
``_PyLexer_restore_fstring_buffers()``. The ``NULL`` pointer arithmetic
(``NULL - valid_pointer``) is now guarded with explicit ``NULL`` checks.

..

.. date: 2026-02-12-19-01-13
.. gh-issue: 141510
.. nonce: KlKjZg
.. section: Core and Builtins

Add built-in :class:`frozendict` type. Patch by Victor Stinner.

..

.. date: 2026-02-12-12-39-50
.. gh-issue: 144681
.. nonce: Ns2OT2
.. section: Core and Builtins

Fix a JIT assertion failure when a conditional branch jumps to the same
target as the fallthrough path.

..

.. date: 2026-02-11-13-30-11
.. gh-issue: 143300
.. nonce: yjB63-
.. section: Core and Builtins

Add :c:func:`PyUnstable_SetImmortal` C-API function to mark objects as
:term:`immortal`.

..

.. date: 2026-02-11-11-28-25
.. gh-issue: 144702
.. nonce: XjFumv
.. section: Core and Builtins

Clarify the error message raised when a class pattern is used to match on a
non-class object.

..

.. date: 2026-02-08-13-14-00
.. gh-issue: 144569
.. nonce: pjlJVe
.. section: Core and Builtins

Optimize ``BINARY_SLICE`` for list, tuple, and unicode by avoiding temporary
``slice`` object creation.

..

.. date: 2026-02-06-21-45-52
.. gh-issue: 144438
.. nonce: GI_uB1LR
.. section: Core and Builtins

Align the QSBR thread state array to a 64-byte cache line boundary to avoid
false sharing in the :term:`free-threaded build`.

..

.. date: 2025-12-06-15-46-32
.. gh-issue: 142349
.. nonce: IdTuYL
.. section: Core and Builtins

Implement :pep:`810`. Patch by Pablo Galindo and Dino Viehland.

..

.. date: 2025-11-09-15-44-58
.. gh-issue: 141226
.. nonce: KTb_3F
.. section: Core and Builtins

Deprecate :pep:`456` support for providing an external definition of the
string hashing scheme. Removal is scheduled for Python 3.19. Patch by
Bénédikt Tran.

..

.. date: 2025-09-15-13-28-48
.. gh-issue: 138912
.. nonce: 61EYbn
.. section: Core and Builtins

Improve :opcode:`MATCH_CLASS` performance by up to 52% in certain cases.
Patch by Marc Mueller.

..

.. date: 2025-02-19-21-06-30
.. gh-issue: 130327
.. nonce: z3TaR8
.. section: Core and Builtins

Fix erroneous clearing of an object's :attr:`~object.__dict__` if
overwritten at runtime.

..

.. date: 2023-07-26-00-03-00
.. gh-issue: 80667
.. nonce: N7Dh8B
.. section: Core and Builtins

Literals using the ``\N{name}`` escape syntax can now construct CJK
ideographs and Hangul syllables using case-insensitive names.

..

.. date: 2026-03-03-14-59-57
.. gh-issue: 142417
.. nonce: HiNP5j
.. section: C API

Restore private provisional ``_Py_InitializeMain()`` function removed in
Python 3.14. Patch by Victor Stinner.

..

.. date: 2026-02-24-14-46-05
.. gh-issue: 144748
.. nonce: uhnFtE
.. section: C API

:c:func:`PyErr_CheckSignals` now raises the exception scheduled by
:c:func:`PyThreadState_SetAsyncExc`, if any.

..

.. date: 2026-02-18-15-12-34
.. gh-issue: 144981
.. nonce: 4ZdM63
.. section: C API

Made :c:func:`PyUnstable_Code_SetExtra`, :c:func:`PyUnstable_Code_GetExtra`,
and :c:func:`PyUnstable_Eval_RequestCodeExtraIndex` thread-safe on the
:term:`free threaded <free threading>` build.

..

.. date: 2026-02-12-19-03-31
.. gh-issue: 141510
.. nonce: U_1tjz
.. section: C API

Add the following functions for the new :class:`frozendict` type:

* :c:func:`PyAnyDict_Check`
* :c:func:`PyAnyDict_CheckExact`
* :c:func:`PyFrozenDict_Check`
* :c:func:`PyFrozenDict_CheckExact`
* :c:func:`PyFrozenDict_New`

Patch by Victor Stinner.

..

.. date: 2026-02-10-14-49-49
.. gh-issue: 121617
.. nonce: 57vMqa
.. section: C API

``Python.h`` now also includes ``<string.h>`` in the limited C API version
3.11 and newer to fix the :c:macro:`Py_CLEAR` macro which uses ``memcpy()``.
Patch by Victor Stinner.

..

.. date: 2026-01-27-18-15-15
.. gh-issue: 144175
.. nonce: qHK5Jf
.. section: C API

Add :c:func:`PyArg_ParseArray` and :c:func:`PyArg_ParseArrayAndKeywords`
functions to parse arguments of functions using the :c:macro:`METH_FASTCALL`
calling convention. Patch by Victor Stinner.

..

.. date: 2026-02-27-18-10-02
.. gh-issue: 144533
.. nonce: 21fk9L
.. section: Build

Use wasmtime's ``--argv0`` to auto-discover sysconfig in WASI builds

..

.. date: 2026-02-22-13-35-20
.. gh-issue: 145110
.. nonce: KgWofW
.. section: Build

Fix targets "Clean" and "CLeanAll" in case of PGO builds on Windows. Patch
by Chris Eibl.

..

.. date: 2026-02-10-18-26-04
.. gh-issue: 144679
.. nonce: FIH73W
.. section: Build

When building with Visual Studio 2026 (Version 18), use PlatformToolSet v145
by default. Patch by Chris Eibl.

..

.. date: 2026-02-10-16-59-56
.. gh-issue: 144675
.. nonce: Wrf3Es
.. section: Build

Update to WASI SDK 30.

..

.. date: 2025-07-21-00-33-38
.. gh-issue: 136677
.. nonce: Y1_3ec
.. section: Build

Introduce executable specific linker flags to ``./configure``.
