CVE-2020-7212Network attack vector

CPU exhaustion via quadratic URL normalization

Published Mar 6, 2020 · Updated Aug 4, 2024

Algorithmic denial of service in urllib3 1.25.2 through 1.25.7 allows remote attackers to exhaust CPU through crafted URL input. The _encode_invalid_chars function collects duplicate percent encodings, then repeatedly scans and replaces them, producing quadratic processing time. Exposure requires an application to pass attacker-controlled URL data into this code path; Red Hat disputes that the added CPU use is operationally meaningful.

CVSS severity8.7
High
EPSS probability3.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic denial of service in urllib3 1.25.2 through 1.25.7 allows remote attackers to exhaust CPU through crafted URL input. The _encode_invalid_chars function collects duplicate percent encodings, then repeatedly scans and replaces them, producing quadratic processing time. Exposure requires an application to pass attacker-controlled URL data into this code path; Red Hat disputes that the added CPU use is operationally meaningful.

The record

CVE
CVE-2020-7212
Published
Mar 6, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 6, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.7GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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