UBUNTU-CVE-2020-7212 (CVE-2020-7212)

Vulnerability from osv_ubuntu – Published: 2020-03-06 20:15 – Updated: 2025-07-16 04:55 – Source website
Withdrawn 2025-07-18 VLAI
Details

The _encode_invalid_chars function in util/url.py in the urllib3 library 1.25.2 through 1.25.7 for Python allows a denial of service (CPU consumption) because of an inefficient algorithm. The percent_encodings array contains all matches of percent encodings. It is not deduplicated. For a URL of length N, the size of percent_encodings may be up to O(N). The next step (normalize existing percent-encoded bytes) also takes up to O(N) for each step, so the total time is O(N^2). If percent_encodings were deduplicated, the time to compute _encode_invalid_chars would be O(kN), where k is at most 484 ((10+6*2)^2).

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "python3-urllib3",
            "binary_version": "1.25.8-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "python-urllib3",
        "purl": "pkg:deb/ubuntu/python-urllib3@1.25.8-2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.8-2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.24.1-1ubuntu1",
        "1.24.1-1ubuntu2",
        "1.25.8-1"
      ]
    }
  ],
  "aliases": [],
  "details": "The _encode_invalid_chars function in util/url.py in the urllib3 library 1.25.2 through 1.25.7 for Python allows a denial of service (CPU consumption) because of an inefficient algorithm. The percent_encodings array contains all matches of percent encodings. It is not deduplicated. For a URL of length N, the size of percent_encodings may be up to O(N). The next step (normalize existing percent-encoded bytes) also takes up to O(N) for each step, so the total time is O(N^2). If percent_encodings were deduplicated, the time to compute _encode_invalid_chars would be O(kN), where k is at most 484 ((10+6*2)^2).",
  "id": "UBUNTU-CVE-2020-7212",
  "modified": "2025-07-16T04:55:36Z",
  "published": "2020-03-06T20:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2020-7212"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/pull/1787"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/blob/master/CHANGES.rst"
    },
    {
      "type": "REPORT",
      "url": "https://pypi.org/project/urllib3/1.25.8/"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2020-7212"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2020-7212"
  ],
  "withdrawn": "2025-07-18T16:45:44Z"
}



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