CVE-2024-12254

Name	CVE-2024-12254
Description	Starting in Python 3.12.0, the asyncio._SelectorSocketTransport.writelines() method would not "pause" writing and signal to the Protocol to drain the buffer to the wire once the write buffer reached the "high-water mark". Because of this, Protocols would not periodically drain the write buffer potentially leading to memory exhaustion. This vulnerability likely impacts a small number of users, you must be using Python 3.12.0 or later, on macOS or Linux, using the asyncio module with protocols, and using .writelines() method which had new zero-copy-on-write behavior in Python 3.12.0 and later. If not all of these factors are true then your usage of Python is unaffected.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1089235, 1089236

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python3.11 (PTS)	bookworm	3.11.2-6+deb12u8	fixed
	bookworm (security)	3.11.2-6+deb12u3	fixed
python3.13 (PTS)	trixie	3.13.5-2+deb13u3	fixed
	forky, sid	3.13.15-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Debian Bugs
python3.11	source	(unstable)	(not affected)
python3.12	source	(unstable)	3.12.8-2	1089236
python3.13	source	(unstable)	3.13.1-2	1089235
python3.9	source	(unstable)	(not affected)

Notes

- python3.11 <not-affected> (Vulnerable code introduced in 3.12)
- python3.9 <not-affected> (Vulnerable code introduced in 3.12)
https://github.com/python/cpython/issues/127655
https://github.com/python/cpython/pull/127656
https://mail.python.org/archives/list/security-announce@python.org/thread/H4O3UBAOAQQXGT4RE3E4XQYR5XLROORB/
https://github.com/python/cpython/commit/71e8429ac8e2adc10084ab5ec29a62f4b6671a82 (3.13-branch)
https://github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5 (3.12-branch)