The build-helper programs (`Programs/_freeze_module` and `_bootstrap_python`) don't need to link extension modules that they don't need.
This PR makes sure the helper programs get only the modules they need to do their job, regardless of what the build configuration sets for the final built runtime and interpreter.
This follows the same pattern as what `PCbuild/_freeze_module.vcxproj` does with `PC/config_minimal.c`, and lets "extra" builtin modules (from `Setup.local` or `MODULE_BUILDTYPE=static`) depend on frozen modules or `getpath`.
ZSTD_freeCCtx() frees a dictionary loaded with ZSTD_CCtx_loadDictionary()
before it stops the worker threads. Make libzstd wait for unfinished
jobs before freeing the compression context of a ZstdCompressor that
uses worker threads and a ZstdDict.
Works around https://github.com/facebook/zstd/issues/4862
The garbage collector could release a ZstdCompressor's dictionary, or
the digested dictionaries cached by the ZstdDict, while worker threads
of the compression context were still reading them. They are now only
released on deallocation, after the context has been freed.
ANT-2026-CT3P1CSJ
+ Visit the type in the compressor and decompressor traverse; move NEWS to Library
A cursor exposed its description tuple before filling in all the columns, so an allocation failure or a reader on a free-threaded build could encounter an unset tuple entry. An allocation failure could also clear lastrowid and crash the next execute. Build new metadata before replacing the old values and synchronize reads and writes. Keep a strong reference to each row or text factory while it is called so replacing the factory during a fetch cannot destroy an active callable.
A raw read can reinitialize a TextIOWrapper as write-only, and codec callbacks or finalizers can release an encoder, decoder, or decoded chunk while a read or write still needs it. This can crash the interpreter. Check that a decoder is still available after reading, keep codecs alive across calls, and read the chunk length before transferring ownership. Also recheck StringIO after converting the truncate size because __index__() can close the stream.
The ssl module now rejects TLS certificate chains that contain any of a set of
compromised eMudhra intermediate CA keys. This is an extraordinary measure and
a last line of defense: removing trust is primarily the job of the platform root
store, and the built-in denylist only blocks connections while that update has
not yet reached the OS, a container image, or a bundled trust store in various
Python packages. Entries are added to the denylist only under a very high
threshold.
The denylist matches on the public key (the SHA-256 digest of the RFC-5280
SubjectPublicKeyInfo), so it also covers the cross-signed certificates that
reuse one of the distrusted keys.
---------
Signed-off-by: Christian Heimes <[email protected]>
Co-authored-by: Claude Opus 4.8 (1M context) <[email protected]>
An external timer can run Python again when the profiler converts or releases its result or reports an unraisable exception. Calling clear() or disable() at that point could free a profiling context still in use. Calling Profiler.__init__() from the timer could also destroy the active callable. Keep the guard active through result handling and reject reinitialization while an external timer is running.
The HZ encoder can consume a tilde after writing only its first escape byte. A split ISO-2022 escape can exceed the incremental decoder’s pending buffer, and a reset can leave the previous character set selected. Reserve space for both HZ bytes before consuming the tilde, allow the full pending escape, and restore the initial ISO-2022 state on reset. Keep the native codec table and the active encoder error policy alive so replacing their Python owners cannot leave a codec using freed memory.
A character data callback can disable buffering or remove the next event handler during a flush. Interning an attribute name can also change ordered_attributes while pyexpat is filling the attribute container. Using the freed buffer, cleared handler, or wrong container type can crash the interpreter. Clear the buffered length before dispatch, keep the active handler alive, recheck the buffer and handlers after callbacks, and use one attribute mode for the whole start event.
Include the client's certificate when the session was resumed from a
ticket, and return [] instead of raising AttributeError when the client
sent no certificate.
ANT-2026-2RMA0IPV
Co-authored-by: Bénédikt Tran <[email protected]>
Heap types have no static type object so switch from `Py_Is` to an
assert that the shadowed `tp_new` / `tp_init` function is the expected
one to validate the vectorcall is only used with the right type.
Heap types can have zero-argument `__new__` and `__init__` so add
support for that producing the same error message via a new helper
`_PyArg_NoPositionalStack()`.
Co-authored-by: Claude Opus 5.5 <[email protected]>
A size object's __index__() can close a BytesIO or export its buffer after truncate() checks the stream. Continuing can dereference a cleared buffer or resize storage behind a live view. Recheck the stream state after size conversion. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_memoryio.py.
When a SQL parameter sequence is an exact list, sqlite3 retrieved an element as a borrowed reference before taking ownership. On free-threaded builds another thread can replace it in between, so binding can use a freed object and crash. Fetch a strong reference atomically. Backport to 3.15 and 3.14.
GH-156483 made `getpath` locate a venv's base installation relative to the *resolved* base executable instead of the `home` key in `pyvenv.cfg`. When the resolved executable lives outside the installation tree (e.g. a launcher binary symlinked into it), nothing is found there and discovery falls back to the compiled-in `PREFIX`. The venv then either fails to start or silently runs with another installation's standard library.
This PR:
- Keeps GH-156483's behavior when the resolved executable's directory locates a standard library (`pybuilddir.txt`, the stdlib zip, or `os.py`). Otherwise it keeps searching from `home`, as before GH-156483.
- In that fallback case, still searches the resolved executable's directory for `lib-dynload` when determining `exec_prefix`: after `prefix`, before `home` and the compiled-in `EXEC_PREFIX`. Layouts with a separate exec prefix (e.g. `./configure --exec-prefix`) then keep loading extension modules from the right place, and a stale `lib-dynload` near the `home` symlink can't take precedence over the one beside the resolved executable.
The tests added by GH-156483 pass unchanged. Three new `test_getpath` cases cover the launcher-outside-the-installation and separate-exec-prefix layouts, and a misleading `lib-dynload` near `home`; each fails without this change.
<details>
<summary>Reproducer</summary>
On `main` (0a86a34), with a plain `./configure --prefix=$HOME/py-under-test && make && make install`:
```sh
#!/bin/sh
# Usage: venv-home-repro.sh <installed-prefix> <X.Y>
set -eu
PREFIX=$1; VER=$2
W=$(mktemp -d)
mkdir -p "$W/runtime/bin" "$W/runtime/lib" "$W/launcher"
cp -R "$PREFIX/lib/python$VER" "$W/runtime/lib/"
cp "$PREFIX/bin/python$VER" "$W/launcher/python3"
ln -s "$W/launcher/python3" "$W/runtime/bin/python3"
PYTHONHOME="$W/runtime" "$W/runtime/bin/python3" -m venv --without-pip "$W/venv"
grep '^home' "$W/venv/pyvenv.cfg"
echo "expected base_prefix: $W/runtime"
"$W/venv/bin/python" -c 'import os, sys; print("actual base_prefix:", sys.base_prefix); print("os.py loaded from:", os.__file__)'
```
Before:
```
home = /tmp/tmp.NFug9wEr4h/runtime/bin
expected base_prefix: /tmp/tmp.NFug9wEr4h/runtime
actual base_prefix: /home/user/py-under-test
os.py loaded from: /home/user/py-under-test/lib/python3.16/os.py
```
(With `$HOME/py-under-test/lib/python3.16` removed, the venv instead fails with `ModuleNotFoundError: No module named 'encodings'`.)
After:
```
home = /tmp/tmp.8Zne2otFrw/runtime/bin
expected base_prefix: /tmp/tmp.8Zne2otFrw/runtime
actual base_prefix: /tmp/tmp.8Zne2otFrw/runtime
os.py loaded from: /tmp/tmp.8Zne2otFrw/runtime/lib/python3.16/os.py
```
</details>
A str subclass can override replace() and return a non-string while TextIOWrapper.write() translates newlines. The C implementation then treats the result as Unicode and can crash. Reject an invalid replacement with TypeError. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_io.py.
_as_parameter_ chains were recursion-checked for typed arguments but not for foreign calls without argtypes. A cyclic chain could exhaust the C stack and crash before the function was called. Apply the same recursion guard to untyped conversion. Backport to 3.15 and 3.14.
Adds the ability to build Emscripten statically, so that it can be linked in as
an embedded library. Includes a test of the embedding case.
---------
Co-authored-by: Claude Fable 5.1 <[email protected]>
Co-authored-by: Russell Keith-Magee <[email protected]>
When an instance advertises a __class__ different from its actual type, ABCMeta.__instancecheck__ performs two subclass checks. The first callback can change the instance's actual type and allow its old type to be collected before the second check, causing a crash. Keep the original type alive through both checks. Backport to 3.15 and 3.14.
Clearing an Unpickler memo left its sequential index and sparse entries intact, so reusing the unpickler for an independent record could raise UnpicklingError or retrieve an object from a previous record. Replace the memo and reset all of its state before releasing the old entries. Backport to 3.15; manually backport only the counter reset to 3.14, which has no sparse memo.
When creating a ctypes structure subclass, cloning its layout initially copied pointers to buffers owned by the base class. If a later allocation failed, cleaning up the subclass could free those buffers, leaving the base with invalid metadata and potentially causing a crash. Detach the owned pointers until their copies have been allocated. Backport to 3.15 and 3.14.
If allocating a thread-local object’s internal dictionary or watchdog set fails, a subclass finalizer can run with that state missing. Accessing a thread-local attribute then dereferences the missing state and crashes; allocate both containers before creating the object. Backport to 3.15 and 3.14.
If allocating a SimpleQueue buffer fails, the partially constructed object reports nonzero capacity despite having no storage. A subclass finalizer that calls put() then writes through a NULL pointer and crashes; publish the capacity only after allocation succeeds. Backport to 3.15 and 3.14.
Drop the basic repeat/in-place-repeat tests: test_abstract.py now
covers those paths via _testlimitedcapi (including corner counts,
MemoryError, TypeError and NULL cases). Keep the subtype and error
tests unique to this PR.
Add test_sequence_repeat_numeric_fallback for the previously
untested nb_multiply fallback in PySequence_Repeat.
Assert exact result types with assertIs: comparing against
CustomList(...) only checks contents, and repeat of a builtin
subtype returns the exact builtin type.
Co-authored-by: Muse Code (Meta Muse Spark)
Co-authored-by: Lukasz Langa <[email protected]>
