CVE-2020-7212
Published: 6 March 2020
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).
Notes
| Author | Note |
|---|---|
| leosilva | Introduced by a74c9cfbaed9f811e7563cfc3dce894928e0221a fixed by a2697e7c6b275f05879b60f593c5854a816489f0 Introduced in 1.25.2 and fixed in 1.25.8 |
Priority
Status
| Package | Release | Status |
|---|---|---|
|
python-urllib3 Launchpad, Ubuntu, Debian |
bionic |
Not vulnerable
|
| eoan |
Not vulnerable
|
|
| focal |
Not vulnerable
(1.25.8-2)
|
|
| trusty |
Not vulnerable
|
|
| upstream |
Released
(1.25.8)
|
|
| xenial |
Not vulnerable
|
|
|
Patches: upstream: https://github.com/urllib3/urllib3/commit/a2697e7c6b275f05879b60f593c5854a816489f0 |
||
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.5 |
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | High |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |