CVE-2024-12254
Published: December 7, 2024Last modified: August 15, 2025
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.5 |
| Attack Vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | python3 | Not affected (3.11.3-r0) |
| 25 LTS | python3 | Not affected (3.12.10-r1) | |
| Stream | python3 | Fixed (3.12.8-r1) | |
| Hardened Containers | 23 LTS | python3 | Not affected (3.11.3-r0) |
| Stream | python3 | Fixed (3.12.8-r1) |
References
- http://www.openwall.com/lists/oss-security/2024/12/06/1
- https://github.com/python/cpython/commit/71e8429ac8e2adc10084ab5ec29a62f4b6671a82
- https://github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5
- https://github.com/python/cpython/commit/e991ac8f2037d78140e417cc9a9486223eb3e786
- https://github.com/python/cpython/issues/127655
- https://github.com/python/cpython/pull/127656
- https://mail.python.org/archives/list/[email protected]/thread/H4O3UBAOAQQXGT4RE3E4XQYR5XLROORB/
- https://security.netapp.com/advisory/ntap-20250404-0010/