{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "819095fa886db98cf43b6f0e66ba19c83d64d3c0"
            },
            {
              "fixed": "358cbf29c4e364c59930e53a270116249581eaa3"
            }
          ],
          "repo": "https://github.com/pyca/pyopenssl",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-5pwr-322w-8jr4"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-120"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27459.json"
  },
  "details": "pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.",
  "id": "CVE-2026-27459",
  "modified": "2026-04-01T23:08:25.688744626Z",
  "published": "2026-03-17T23:34:28.483Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27459.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27459"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U",
      "type": "CVSS_V4"
    }
  ],
  "summary": "pyOpenSSL DTLS cookie callback buffer overflow"
}