CVE-2020-7212

Name	CVE-2020-7212
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).
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-urllib3 (PTS)	bullseye	1.26.5-1~exp1	fixed
	bookworm	1.26.12-1	fixed
	sid, trixie	2.0.7-2	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version
python-urllib3	source	jessie	(not affected)
python-urllib3	source	stretch	(not affected)
python-urllib3	source	buster	(not affected)
python-urllib3	source	(unstable)	1.25.8-1

Notes

[buster] - python-urllib3 <not-affected> (Vulnerable code introduced later)
[stretch] - python-urllib3 <not-affected> (Vulnerable code introduced later)
[jessie] - python-urllib3 <not-affected> (Vulnerable code introduced later)
https://github.com/urllib3/urllib3/pull/1787
Introduced by: https://github.com/urllib3/urllib3/commit/a74c9cfbaed9f811e7563cfc3dce894928e0221a (1.25.2)
Fixed by: https://github.com/urllib3/urllib3/commit/a2697e7c6b275f05879b60f593c5854a816489f0 (1.25.8)