pysec-2020-149
Vulnerability from pysec
Published
2020-03-06 20:15
Modified
2020-03-09 16:55
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).

Impacted products
Name purl
urllib3 pkg:pypi/urllib3
Aliases


To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "urllib3",
        "purl": "pkg:pypi/urllib3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "a74c9cfbaed9f811e7563cfc3dce894928e0221a"
            }
          ],
          "repo": "https://github.com/urllib3/urllib3",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "1.25.2"
            },
            {
              "fixed": "1.25.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.25.2",
        "1.25.3",
        "1.25.4",
        "1.25.5",
        "1.25.6",
        "1.25.7"
      ]
    }
  ],
  "aliases": [
    "CVE-2020-7212",
    "GHSA-hmv2-79q8-fv6g"
  ],
  "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": "PYSEC-2020-149",
  "modified": "2020-03-09T16:55:00Z",
  "published": "2020-03-06T20:15:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/urllib3/urllib3/blob/master/CHANGES.rst"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/urllib3/1.25.8/"
    },
    {
      "type": "FIX",
      "url": "https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-hmv2-79q8-fv6g"
    }
  ]
}


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