CVE-2021-22881
The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability.
Does this matter?
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.
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.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 87.30% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-601
- Affected
- rubyonrails/rails · fedoraproject/fedora
- Source
- support@hackerone.com
EPSS 87.3% since 3 November 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.openwall.com/lists/oss-security/2021/05/05/2Mailing List, Mitigation, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/08/20/1Mailing List, Mitigation, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/12/14/5Exploit, Mailing List, Patch
- https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/Patch, Third Party Advisory
- https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130Mitigation, Patch, Vendor Advisory
- https://hackerone.com/reports/1047447Exploit, Patch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/
- http://www.openwall.com/lists/oss-security/2021/05/05/2Mailing List, Mitigation, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/08/20/1Mailing List, Mitigation, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/12/14/5Exploit, Mailing List, Patch
- https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/Patch, Third Party Advisory
- https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130Mitigation, Patch, Vendor Advisory
- https://hackerone.com/reports/1047447Exploit, Patch, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.