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).

Published: 2020-03-06 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2020-7212 is rated Moderate Risk (62.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 3.29%). Core evidence: EPSS rose +2.50% over the last day, indicating growing attacker interest. Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-7212

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.79% 3.29% +2.50%
2 2026-06-11 1.15% 0.79% -0.36%
3 2026-05-27 1.15%

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-7212

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 3.6 [email protected]
7.8 2.0 HIGH
AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
10.0 6.9 [email protected]

Weakness enumeration for CVE-2020-7212

GitHub Security Advisory for CVE-2020-7212

GHSA-hmv2-79q8-fv6g · Severity: high · Ecosystem: pip — Uncontrolled Resource Consumption in urllib3

OS Trackers for CVE-2020-7212

vendor priority summary link
debian not yet assigned CVE-2020-7212 not yet assigned priority: Debian including 1 source packages (python-urllib3), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-7212
redhat https://access.redhat.com/security/cve/CVE-2020-7212
ubuntu medium CVE-2020-7212 medium priority: Ubuntu including 1 source packages (python-urllib3), 6 status rows across 6 suites (bionic, eoan, focal, trusty, upstream, xenial): not-affected 5, released 1. https://ubuntu.com/security/CVE-2020-7212

Affected software / configurations for CVE-2020-7212

Vendor Product Version Raw CPE
python urllib3 >= 1.25.2, <= 1.25.7 cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*

References for CVE-2020-7212

cvelogic Threat Intelligence