GHSA-RPRW-H62V-C2W7

Vulnerability from github – Published: 2019-01-04 17:45 – Updated: 2026-07-01 17:39
VLAI
Summary
PyYAML insecurely deserializes YAML strings leading to arbitrary code execution
Details

In PyYAML before 5.1, the yaml.load() API could execute arbitrary code. In other words, yaml.safe_load is not used.

This was intended to be fixed in 4.1, but due to breaking changes, 4.1 was yanked and 5.1 contains the patch for CVE-2017-18342.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "PyYAML"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2017-18342"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-06-16T21:55:26Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "In PyYAML before 5.1, the `yaml.load()` API could execute arbitrary code. In other words, `yaml.safe_load` is not used.\n\nThis was intended to be fixed in 4.1, but due to [breaking changes](https://github.com/yaml/pyyaml/issues/192#issuecomment-401491470), 4.1 was yanked and 5.1 [contains](https://github.com/yaml/pyyaml/issues/207#issuecomment-472520007) the patch for CVE-2017-18342.",
  "id": "GHSA-rprw-h62v-c2w7",
  "modified": "2026-07-01T17:39:14Z",
  "published": "2019-01-04T17:45:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2017-18342"
    },
    {
      "type": "WEB",
      "url": "https://github.com/marshmallow-code/apispec/issues/278"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yaml/pyyaml/issues/193"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yaml/pyyaml/issues/207#issuecomment-472520007"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yaml/pyyaml/pull/74"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yaml/pyyaml/commit/7b68405c81db889f83c32846462b238ccae5be80"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2018-49.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/yaml/pyyaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yaml/pyyaml/blob/master/CHANGES"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JEX7IPV5P2QJITAMA5Z63GQCZA5I6NVZ"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KSQQMRUQSXBSUXLCRD3TSZYQ7SEZRKCE"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/M6JCFGEIEOFMWWIXGHSELMKQDD4CV2BA"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202003-45"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "PyYAML insecurely deserializes YAML strings leading to arbitrary code execution"
}


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