{"cve":"CVE-2021-22903","nvd":{"published":"2021-06-11T16:15:11.437","modified":"2026-06-17T03:37:59.600","status":"Modified","description":"The actionpack ruby gem before 6.1.3.2 suffers from a possible open redirect vulnerability. Specially crafted Host headers in combination with certain \"allowed host\" formats can cause the Host Authorization middleware in Action Pack to redirect users to a malicious website. This is similar to CVE-2021-22881. Strings in config.hosts that do not have a leading dot are converted to regular expressions without proper escaping. This causes, for example, `config.hosts << \"sub.example.com\"` to permit a request with a Host header value of `sub-example.com`.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-601"],"references":["https://discuss.rubyonrails.org/t/cve-2021-22903-possible-open-redirect-vulnerability-in-action-pack/77867","https://hackerone.com/reports/1148025","https://discuss.rubyonrails.org/t/cve-2021-22903-possible-open-redirect-vulnerability-in-action-pack/77867","https://hackerone.com/reports/1148025"],"products":["rubyonrails:rails"],"source":"nvd","synced_at":"2026-10-19T21:20:07.141963181+00:00"},"epss":{"cve":"CVE-2021-22903","score":0.0123,"percentile":0.68938,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-5hq2-xf89-9jxq","url":"https://osv.dev/vulnerability/GHSA-5hq2-xf89-9jxq","summary":"Possible Open Redirect Vulnerability in Action Pack","modified":"2024-02-16T08:18:07.647142Z","packages":[{"ecosystem":"RubyGems","name":"actionpack","purl":"pkg:gem/actionpack","ranges":[">=6.1.0.rc2 <6.1.3.2"],"fixed":["6.1.3.2"]}]}],"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."]}