CVE-2021-20220

Severity: medium (CVSS 4.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-02-23 · updated 2026-06-17
Weakness: CWE-444

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.

Affected products

Active IQ Unified Manager for VMware vSphere, Linux, and Microsoft Windows: all versions
NetApp OnCommand Workflow Automation: all versions
Red Hat undertow: before 2.0.34; from 2.1.0 before 2.1.6 — fixed in 2.0.34, 2.1.6

How to fix

Upgrade to a fixed version: Red Hat undertow 2.0.34, 2.1.6. Check the vendor advisory for mitigations.

References

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