GHSA-5PWR-322W-8JR4

Vulnerability from github – Published: 2026-03-16 16:22 – Updated: 2026-03-19 18:28
VLAI
Summary
pyOpenSSL DTLS cookie callback buffer overflow
Details

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.

Cookie values that are too long are now rejected.

Severity
7.2 (High)
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
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pyopenssl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "22.0.0"
            },
            {
              "fixed": "26.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27459"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-120"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-16T16:22:29Z",
    "nvd_published_at": "2026-03-18T00:16:19Z",
    "severity": "HIGH"
  },
  "details": "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.\n\nCookie values that are too long are now rejected.",
  "id": "GHSA-5pwr-322w-8jr4",
  "modified": "2026-03-19T18:28:11Z",
  "published": "2026-03-16T16:22:29Z",
  "references": [
    {
      "type": "WEB",
      "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": "WEB",
      "url": "https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pyca/pyopenssl"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst"
    }
  ],
  "schema_version": "1.4.0",
  "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"
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.