Vulnerability Details CVE-2020-7212
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).
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 60.1%
CVSS Severity
CVSS v3 Score 7.5
CVSS v2 Score 7.8
References
- https://github.com/urllib3/urllib3/blob/master/CHANGES.rst
- https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a
- https://pypi.org/project/urllib3/1.25.8/
- https://github.com/urllib3/urllib3/blob/master/CHANGES.rst
- https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a
- https://pypi.org/project/urllib3/1.25.8/
Products affected by CVE-2020-7212
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cpe:2.3:a:python:urllib3:1.25.2
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cpe:2.3:a:python:urllib3:1.25.3
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cpe:2.3:a:python:urllib3:1.25.4
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cpe:2.3:a:python:urllib3:1.25.5
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cpe:2.3:a:python:urllib3:1.25.6
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cpe:2.3:a:python:urllib3:1.25.7