{"id":"CVE-2021-20220","aliases":["GHSA-qjwc-v72v-fq6r"],"url":"https://o3.security/vulnerability/CVE-2021-20220","summary":"HTTP request smuggling in Undertow","details":"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.","published":"2021-02-23T18:15:13.397Z","modified":"2026-07-09T00:22:14.674380Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Maven","name":"io.undertow:undertow-core","fixedVersion":"2.1.6"},{"ecosystem":"Maven","name":"io.undertow:undertow-core","fixedVersion":"2.0.34"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20220210-0013/"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=1923133"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-09T00:22:14.674380Z"}}