Vulnerability from bitnami_vulndb
Published
2025-08-11 13:52
Modified
2025-08-11 14:19
Summary
Unbounded memory buffering in SelectorSocketTransport.writelines()
Details

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.

To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "libpython",
        "purl": "pkg:bitnami/libpython"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.12.0"
            },
            {
              "fixed": "3.12.9"
            },
            {
              "introduced": "3.13.0"
            },
            {
              "fixed": "3.13.2"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "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",
          "type": "CVSS_V4"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-12254"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*"
    ],
    "severity": "High"
  },
  "details": "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 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.",
  "id": "BIT-libpython-2024-12254",
  "modified": "2025-08-11T14:19:40.295Z",
  "published": "2025-08-11T13:52:40.569Z",
  "references": [
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2024/12/06/1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/71e8429ac8e2adc10084ab5ec29a62f4b6671a82"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/e991ac8f2037d78140e417cc9a9486223eb3e786"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/issues/127655"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/pull/127656"
    },
    {
      "type": "WEB",
      "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/H4O3UBAOAQQXGT4RE3E4XQYR5XLROORB/"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-12254"
    },
    {
      "type": "WEB",
      "url": "https://security.netapp.com/advisory/ntap-20250404-0010/"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "Unbounded memory buffering in SelectorSocketTransport.writelines()"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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