{"id":"UBUNTU-CVE-2020-7212","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where k is at most 484 ((10+6*2)^2).","modified":"2025-07-16T07:41:51.670949Z","published":"2020-03-06T20:15:00Z","withdrawn":"2025-07-18T16:45:44Z","upstream":["CVE-2020-7212"],"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"}],"affected":[{"package":{"name":"python-urllib3","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/python-urllib3@1.25.8-2?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.25.8-2"}]}],"versions":["1.24.1-1ubuntu1","1.24.1-1ubuntu2","1.25.8-1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"python3-urllib3","binary_version":"1.25.8-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-7212.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}