CVE-2021-20220

Name: CVE-2021-20220
Creator: NVD / NIST
Published: 2021-02-23T18:15:13.397+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.8/10EPSS 1.12%

Last modified Jun 17, 2026

CVE-2021-20220 is a medium-severity vulnerability rated 4.8/10 on the CVSS scale. A flaw was found in Undertow. A regression in the fix for CVE-2020-10687 was found. EPSS estimates a 1.12% chance of exploitation in the next 30 days.

Description

A flaw was found in Undertow. A regression in the fix for CVE-2020-10687 was found. HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own. The highest threat from this vulnerability is to data confidentiality and integrity.

Metrics

CVSS 3.1

4.8/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS Probability

1.12%

62.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Redhat	Undertow	< 2.0.34
Redhat	Undertow	>= 2.1.0, < 2.1.6
Netapp	Active Iq Unified Manager	All versions
Netapp	Oncommand Workflow Automation	All versions

References

https://bugzilla.redhat.com/show_bug.cgi?id=1923133Issue Tracking, Vendor Advisory
https://security.netapp.com/advisory/ntap-20220210-0013/Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1923133Issue Tracking, Vendor Advisory
https://security.netapp.com/advisory/ntap-20220210-0013/Third Party Advisory

Timeline

Published: Feb 23, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20220?

How severe is CVE-2021-20220?

CVE-2021-20220 has a CVSS score of 4.8/10 (MEDIUM severity). The EPSS model estimates a 1.12% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20220?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20220?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST