CVEvulnerability
CVE-2020-7212
7.5 HIGH
Official page ↗
- Status
- Modified
- Published
- 2020-03-06
- Last modified
- 2026-06-17
- Assigner
- [email protected]
- CVSS 3.1 ([email protected])
- 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CVSS 2.0 ([email protected])
- 7.8 HIGH — AV:N/AC:L/Au:N/C:N/I:N/A:C
- Weaknesses
- CWE-400
Description
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).
Affected configurations
• python urllib3 (>= 1.25.2 <= 1.25.7)
Related
Weakness · CWE (1)
- CWE-400 Uncontrolled Resource Consumption weakness
References
- https://github.com/urllib3/urllib3/blob/master/CHANGES.rst Release Notes, Third Party Advisory
- https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a Patch, Third Party Advisory
- https://pypi.org/project/urllib3/1.25.8/ Release Notes, Vendor Advisory
- https://github.com/urllib3/urllib3/blob/master/CHANGES.rst Release Notes, Third Party Advisory
- https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a Patch, Third Party Advisory
- https://pypi.org/project/urllib3/1.25.8/ Release Notes, Vendor Advisory