---
title: "CVE-2021-22881: URL Redirection to Untrusted Site | CubePath"
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…"
language: en
source: https://cubepath.com/security/cve/CVE-2021-22881
---

# CVE-2021-22881: URL Redirection to Untrusted Site | CubePath

## 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.

Official description from the CVE record, published by hackerone. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-22881)

## Key data

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score

0.87301 (87.3% probability)

Percentile

99.8%

Scores of

Nov 10, 2026

Model

v2026.06.15

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-601](https://cwe.mitre.org/data/definitions/601.html) URL Redirection to Untrusted Site

## Affected products

Products listed in the CVE record, as the CNA published them.

- https://github.com/rails/rails

  - affected: Fixed in 6.1.2.1, 6.0.3.5

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [hackerone.com/reports/1047447](https://hackerone.com/reports/1047447)
- [discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redi…](https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130)
- [benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans…](https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/)
- [FEDORA-2021-b571fca1b8](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/)  (lists.fedoraproject.org) vendor-advisory
- [\[oss-security\] 20210505 \[CVE-2021-22903\] Possible Open Redirect Vulnerability in Action Pack](http://www.openwall.com/lists/oss-security/2021/05/05/2)  (openwall.com) mailing-list
- [\[oss-security\] 20210819 \[CVE-2021-22942\] Possible Open Redirect in Host Authorization Middleware](http://www.openwall.com/lists/oss-security/2021/08/20/1)  (openwall.com) mailing-list
- [\[oss-security\] 20211214 \[CVE-2021-44528\] Possible Open Redirect in Host Authorization Middleware](http://www.openwall.com/lists/oss-security/2021/12/14/5)  (openwall.com) mailing-list

## Timeline

1. ID reserved Jan 6, 2021
2. Record published Feb 11, 2021
3. Record last updated Aug 3, 2024

## Look up another CVE

## About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

[Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection)

Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:05 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)