CVE-2021-20220

mediumpriority · track · 19EPSS 0.012 · 68 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.20% (68th) EPSS

CVSS 5.8 · medium

Is it mine?

14 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

5.8

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.05.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 4.9

v3.14.8mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 2.5

v3.14.8mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:Nsecondary · OSV

v3.14.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-444USprimaryCWE-444US

affected products (14)

Products and version ranges known to be affected.

Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
Red Hat JBoss Enterprise Application Platform <7.1.8all versionscert_bundDE
Red Hat JBoss Enterprise Application Platform <7.3.6all versionscert_bundDE
Splunk Splunk Enterprise Add-on for JBoss <3.1.1all versionscert_bundDE
Red Hat JBoss Enterprise Application Platform< 7.1.8cert_bundDE
Red Hat JBoss Enterprise Application Platform< 7.3.6cert_bundDE
Splunk Splunk Enterprise≤ Add-on for JBoss <3.1.1cert_bundDE
n/a undertow≤ Undertow 2.2.0.Final, Undertow 2.1.6.Final, Undertow 2.0.34.Finalenisa_euvdEU
netapp active iq unified managerall versionsnvdUScpe:2.3:a:netapp:active_iq_unified_manager:*:*:*:*:*:*:*:*
netapp oncommand workflow automationall versionsnvdUScpe:2.3:a:netapp:oncommand_workflow_automation:*:*:*:*:*:*:*:*
redhat undertow< 2.0.34nvdUScpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
redhat undertow2.1.0 → 2.1.6nvdUScpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
Maven io.undertow:undertow-core< 2.0.34osvUSpkg:maven/io.undertow/undertow-core
Maven io.undertow:undertow-core2.1.0 → 2.1.6osvUSpkg:maven/io.undertow/undertow-core

advisories (2)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2023-1272Red Hat JBoss Enterprise Application Platform: Mehrere SchwachstellenDeutsch2021-03-16csaf · cert_bundDE
Ein entfernter, anonymer oder lokaler Angreifer kann mehrere Schwachstellen in Red Hat JBoss Enterprise Application Platform ausnutzen, um einen Denial-of-Service-Zustand auslösen, Informationen offenzulegen, Daten zu manipulieren, Sicherheitsmaßnahmen zu umgehen oder einen Cross-Site-Scripting-Angriff durchführen.
GHSA-qjwc-v72v-fq6rHTTP request smuggling in Undertow2021-06-16ghsa · osvUS
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.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd osv NVD CVE.org MITRE

published 2021-02-23modified 2026-06-17

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+548 more

references (18)

External citations — patches, advisories, analysis.

scry

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