{"id":"CVE-2021-22881","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-22881","generatedAt":"2026-11-05T01:44:11.121Z","title":"The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability.","description":"The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an 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. Impacted applications will have allowed hosts with a leading dot. When an allowed host contains a leading dot, a specially crafted `Host` header can be used to redirect to a malicious website.","published":"2021-02-11T18:15:17.000Z","lastModified":"2026-06-17T03:37:56.000Z","status":"Modified","sourceIdentifier":"support@hackerone.com","cvss":{"version":"3.1","score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},"cwe":["CWE-601"],"affected":["rubyonrails/rails","fedoraproject/fedora"],"epss":{"score":0.87301,"percentile":0.99753,"date":"2026-11-03","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 87.3%, higher than 100% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"http://www.openwall.com/lists/oss-security/2021/05/05/2","tags":["Mailing List","Mitigation","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"http://www.openwall.com/lists/oss-security/2021/08/20/1","tags":["Mailing List","Mitigation","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"http://www.openwall.com/lists/oss-security/2021/12/14/5","tags":["Exploit","Mailing List","Patch"],"source":"support@hackerone.com"},{"url":"https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/","tags":["Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130","tags":["Mitigation","Patch","Vendor Advisory"],"source":"support@hackerone.com"},{"url":"https://hackerone.com/reports/1047447","tags":["Exploit","Patch","Third Party Advisory"],"source":"support@hackerone.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/","source":"support@hackerone.com"},{"url":"http://www.openwall.com/lists/oss-security/2021/05/05/2","tags":["Mailing List","Mitigation","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2021/08/20/1","tags":["Mailing List","Mitigation","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2021/12/14/5","tags":["Exploit","Mailing List","Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130","tags":["Mitigation","Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://hackerone.com/reports/1047447","tags":["Exploit","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-22881","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}