{"id":"CVE-2024-12254","title":"Starting in Python 3.12.0, the asyncio._SelectorSocketTransport.writelines()\n method would not \"pause\" writing and signal to the Protocol to drain \nthe buffer to the wire once the write buffer reached the \"high-water \nmark\"","summary":"Starting in Python 3.12.0, the asyncio._SelectorSocketTransport.writelines()\n method would not \"pause\" writing and signal to the Protocol to drain \nthe buffer to the wire once the write buffer reached the \"high-water \nmark\". Because of t…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-400","CWE-770","CWE-770"],"published":"2024-12-06","updated":"2026-07-31","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2024-12254","references":[{"url":"https://github.com/python/cpython/commit/71e8429ac8e2adc10084ab5ec29a62f4b6671a82","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/e991ac8f2037d78140e417cc9a9486223eb3e786","label":"cna@python.org"},{"url":"https://github.com/python/cpython/issues/127655","label":"cna@python.org"},{"url":"https://github.com/python/cpython/pull/127656","label":"cna@python.org"},{"url":"https://mail.python.org/archives/list/security-announce@python.org/thread/H4O3UBAOAQQXGT4RE3E4XQYR5XLROORB/","label":"cna@python.org"},{"url":"http://www.openwall.com/lists/oss-security/2024/12/06/1","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20250404-0010/","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.01868,"epssPercentile":0.78094,"ingestedAt":"2026-07-31T15:59:52.064Z","slug":"CVE-2024-12254","body":"## Overview\n\nStarting in Python 3.12.0, the asyncio._SelectorSocketTransport.writelines()\n method would not \"pause\" writing and signal to the Protocol to drain \nthe buffer to the wire once the write buffer reached the \"high-water \nmark\". Because of this, Protocols would not periodically drain the write\n buffer potentially leading to memory exhaustion.\n\n\n\n\n\nThis\n vulnerability likely impacts a small number of users, you must be using\n Python 3.12.0 or later, on macOS or Linux, using the asyncio module \nwith protocols, and using .writelines() method which had new \nzero-copy-on-write behavior in Python 3.12.0 and later. If not all of \nthese factors are true then your usage of Python is unaffected.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":41.3,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[]}