Vulnerability from bitnami_vulndb
Published
2026-10-09 10:52
Modified
2026-10-09 11:12
Summary
Use-after-free of a server-side SSLContext when sni_callback switches contexts
Details

A remote, unauthenticated TLS client can make a server crash or call through a freed pointer if its sni_callback assigns a different context to SSLSocket.context (the documented way to select a certificate per server name) and nothing else keeps the original ssl.SSLContext alive. Typical cases are servers that create an SSLContext per connection or replace it while connections are open; servers that wrap their listening socket with it are not affected.

Mitigation: keep a reference to every SSLContext that sets sni_callback for the lifetime of the server. TLS clients are not affected.

To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "python",
        "purl": "pkg:bitnami/python"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.10.22"
            },
            {
              "introduced": "3.11.0"
            },
            {
              "fixed": "3.11.17"
            },
            {
              "introduced": "3.12.0"
            },
            {
              "fixed": "3.12.15"
            },
            {
              "introduced": "3.13.0"
            },
            {
              "fixed": "3.13.16"
            },
            {
              "introduced": "3.14.0"
            },
            {
              "fixed": "3.14.8"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/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-2026-19445"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*"
    ],
    "severity": "Critical"
  },
  "details": "A remote, unauthenticated TLS client can make a server crash or call\nthrough a freed pointer if its sni_callback assigns a different context to\nSSLSocket.context (the documented way to select a certificate per server\nname) and nothing else keeps the original ssl.SSLContext alive. Typical\ncases are servers that create an SSLContext per connection or replace it\nwhile connections are open; servers that wrap their listening socket with\nit are not affected.\n\n\nMitigation: keep a reference to every SSLContext that sets sni_callback for\nthe lifetime of the server. TLS clients are not affected.",
  "id": "BIT-python-2026-19445",
  "modified": "2026-10-09T11:12:02.352Z",
  "published": "2026-10-09T10:52:46.026Z",
  "references": [
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/09/30/17"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/34a53dce8174da2fceb12fe084a4def02a10053d"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/46133cd57d309652139ada74014aca7665ac552b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/63fab143d94cafae71850831acfb52041ba44af7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/b12968cefe69ca1dcb8606c832ff73ee7dbf4ba8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/cd7e51e7d4563866fbaa1e2521ae69b45daf3698"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/d8717ed01717a9641686e6e6f83f0ab8af235e2c"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/commit/ec44b5a3258cbda947d5e07242ee562ed05ef24b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/issues/156293"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python/cpython/pull/158504"
    },
    {
      "type": "WEB",
      "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/QMQIUQB6WGGC3MI7I3WKQXOYOBDSPPS3/"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19445"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "Use-after-free of a server-side SSLContext when sni_callback switches contexts"
}



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