Release Date: Sept. 6, 2024

This is a security release of Python 3.9

Note: The release you're looking at is Python 3.9.20, a security bugfix release for the legacy 3.9 series. Python 3.12 is now the latest feature release series of Python 3. Get the latest release of 3.12.x here.

Security content in this release

• gh-123678 and gh-116741: Upgrade bundled libexpat to 2.6.3 to fix CVE-2024-28757, CVE-2024-45490, CVE-2024-45491 and CVE-2024-45492.
• gh-118486: os.mkdir() on Windows now accepts mode of 0o700 to restrict the new directory to the current user. This fixes CVE-2024-4030 affecting tempfile.mkdtemp() in scenarios where the base temporary directory is more permissive than the default.
• gh-123067: Fix quadratic complexity in parsing "-quoted cookie values with backslashes by http.cookies. Fixes CVE-2024-7592.
• gh-113171: Fixed various false positives and false negatives in IPv4Address.is_private, IPv4Address.is_global, IPv6Address.is_private, IPv6Address.is_global. Fixes CVE-2024-4032.
• gh-67693: Fix urllib.parse.urlunparse() and urllib.parse.urlunsplit() for URIs with path starting with multiple slashes and no authority. Fixes CVE-2015-2104.
• gh-121957: Fixed missing audit events around interactive use of Python, now also properly firing for python -i, as well as for python -m asyncio. The event in question is cpython.run_stdin.
• gh-122133: Authenticate the socket connection for the socket.socketpair() fallback on platforms where AF_UNIX is not available like Windows.
• gh-121285: Remove backtracking from tarfile header parsing for hdrcharset, PAX, and GNU sparse headers. That’s CVE-2024-6232.
• gh-114572: ssl.SSLContext.cert_store_stats() and ssl.SSLContext.get_ca_certs() now correctly lock access to the certificate store, when the ssl.SSLContext is shared across multiple threads.
• gh-102988: email.utils.getaddresses() and email.utils.parseaddr() now return ('', '') 2-tuples in more situations where invalid email addresses are encountered instead of potentially inaccurate values. Add optional strict parameter to these two functions: use strict=False to get the old behavior, accept malformed inputs. getattr(email.utils, 'supports_strict_parsing', False) can be use to check if the strict paramater is available. This improves the CVE-2023-27043 fix.
• gh-123270: Sanitize names in zipfile.Path to avoid infinite loops (gh-122905) without breaking contents using legitimate characters. That’s CVE-2024-8088.
• gh-121650: email headers with embedded newlines are now quoted on output. The generator will now refuse to serialize (write) headers that are unsafely folded or delimited; see verify_generated_headers. That’s CVE-2024-6923.
• gh-119690: Fixes data type confusion in audit events raised by _winapi.CreateFile and _winapi.CreateNamedPipe.
• gh-116773: Fix instances of <_overlapped.Overlapped object at 0xXXX> still has pending operation at deallocation, the process may crash.
• gh-112275: A deadlock involving pystate.c’s HEAD_LOCK in posixmodule.c at fork is now fixed.

No installers

According to the release calendar specified in PEP 596, Python 3.9 is now in the "security fixes only" stage of its life cycle: the 3.9 branch only accepts security fixes and releases of those are made irregularly in source-only form until October 2025. Python 3.9 isn't receiving regular bug fixes anymore, and binary installers are no longer provided for it. Python 3.9.13 was the last full bugfix release of Python 3.9 with binary installers.

Full Changelog