CVE-2020-7212
Uncontrolled Resource Consumption in urllib3
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).
How to fix CVE-2020-7212
To remediate CVE-2020-7212, upgrade the affected package to a fixed version below.
- —upgrade to 1.25.8-1 or later
- —upgrade to 1.25.8 or later
- —upgrade to a74c9cfbaed9f811e7563cfc3dce894928e0221a or later
Is CVE-2020-7212 being exploited?
Low — EPSS is 1.1%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1.25.8-1
- >= 1.25.2, < 1.25.8
- from 0, < a74c9cfbaed9f811e7563cfc3dce894928e0221a | >= 1.25.2, < 1.25.8
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |