CVE-2024-12254
Unbounded memory buffering in SelectorSocketTransport.writelines()
At a glance
- Severity
- HIGH 8.7
- EPSS
- EPSS 1.87 % · percentile 79 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- PSF
- NVD status
- Deferred
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.
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | HIGH 8.7 | 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 | PSF |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CISA-ADP |
| CVSS 4.0 | HIGH 8.7 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · cna@python.org (Secondary) |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary) |
Weaknesses (CWE)
European references
- ENISA EUVD · EUVD-2024-50718
- GCVE · GCVE-0-2024-12254
CERT-FR advisories
- CERTFR-2025-AVI-1054 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2025-AVI-1036 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0969 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0967 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0905 — Multiples vulnérabilités dans Oracle Database Server · cert.ssi.gouv.fr
- CERTFR-2025-AVI-0641 — Multiples vulnérabilités dans les produits Splunk · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Python Software Foundation · CPython | affected 0 < 3.12.9 ; affected 3.13.0 < 3.13.2 ; affected 3.14.0a1 < 3.14.0a3 |
References
- 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
- https://github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5
- https://github.com/python/cpython/commit/e991ac8f2037d78140e417cc9a9486223eb3e786
- http://www.openwall.com/lists/oss-security/2024/12/06/1
- https://security.netapp.com/advisory/ntap-20250404-0010/
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |