ubuntu-cve-2019-20477
Vulnerability from osv_ubuntu
Published
2020-02-19 04:15
Modified
2025-07-16 04:55
Summary
Details

PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix 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
N/A (UNKNOWN)
low
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python-yaml",
            "binary_version": "5.3-1ubuntu2"
          },
          {
            "binary_name": "python-yaml-dbg",
            "binary_version": "5.3-1ubuntu2"
          },
          {
            "binary_name": "python3-yaml",
            "binary_version": "5.3-1ubuntu2"
          },
          {
            "binary_name": "python3-yaml-dbg",
            "binary_version": "5.3-1ubuntu2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "pyyaml",
        "purl": "pkg:deb/ubuntu/pyyaml@5.3-1ubuntu2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.3-1ubuntu2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "5.1.2-1",
        "5.1.2-1build1",
        "5.3-1ubuntu1"
      ]
    }
  ],
  "aliases": [],
  "details": "PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.",
  "id": "UBUNTU-CVE-2019-20477",
  "modified": "2025-07-16T04:55:22Z",
  "published": "2020-02-19T04:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2019-20477"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/yaml/pyyaml/blob/master/CHANGES"
    },
    {
      "type": "REPORT",
      "url": "https://www.exploit-db.com/download/47655"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2019-20477"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2019-20477"
  ],
  "withdrawn": "2025-07-18T16:45:35Z"
}



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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.

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Detection rules are retrieved from Rulezet.