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.
https://mail.python.org/archives/list/[email protected]/thread/H4O3UBAOAQQXGT4RE3E4XQYR5XLROORB/
https://github.com/python/cpython/pull/127656
https://github.com/python/cpython/issues/127655
https://github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5
https://github.com/python/cpython/commit/71e8429ac8e2adc10084ab5ec29a62f4b6671a82
Published: 2024-12-06
Updated: 2024-12-06
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:P
Severity: Medium
Base Score: 9.1
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Severity: Critical
Base Score: 8.7
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Severity: High