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Vulnerability · Published Feb 23, 2021 · Assigned by redhat

CVE-2021-20220

Medium 4.8

In plain English

A medium-severity security flaw in undertow. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 68% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)4.8Medium
Exploit odds (30 days)1.2%top 31.7% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:14undertow2.2.0-1DEBIAN-CVE-2021-20220
Mavenio.undertow:undertow-core2.1.6GHSA-qjwc-v72v-fq6r
Mavenio.undertow:undertow-core2.0.34GHSA-qjwc-v72v-fq6r
Ubuntu:25.10undertowno fix listedUBUNTU-CVE-2021-20220
Ubuntu:26.04:LTSundertowno fix listedUBUNTU-CVE-2021-20220
Ubuntu:26.10undertowno fix listedUBUNTU-CVE-2021-20220

Affected products (as reported)

VendorProductVersions
n/a undertow Undertow 2.2.0.Final, Undertow 2.1.6.Final, Undertow 2.0.34.Final

Weakness: CWE-444

References