{"cve":"CVE-2021-20220","nvd":{"published":"2021-02-23T18:15:13.397","modified":"2026-06-17T03:33:29.670","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","score":4.8},"cwes":["CWE-444"],"references":["https://bugzilla.redhat.com/show_bug.cgi?id=1923133","https://security.netapp.com/advisory/ntap-20220210-0013/","https://bugzilla.redhat.com/show_bug.cgi?id=1923133","https://security.netapp.com/advisory/ntap-20220210-0013/"],"products":["netapp:active_iq_unified_manager","netapp:oncommand_workflow_automation","redhat:undertow"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-20220","score":0.012,"percentile":0.68193,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-qjwc-v72v-fq6r","url":"https://osv.dev/vulnerability/GHSA-qjwc-v72v-fq6r","summary":"HTTP request smuggling in Undertow","modified":"2024-02-17T05:25:37.784324Z","packages":[{"ecosystem":"Maven","name":"io.undertow:undertow-core","purl":"pkg:maven/io.undertow/undertow-core","ranges":[">=2.1.0 <2.1.6"],"fixed":["2.1.6"]},{"ecosystem":"Maven","name":"io.undertow:undertow-core","purl":"pkg:maven/io.undertow/undertow-core","ranges":["<2.0.34"],"fixed":["2.0.34"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}