CVE-2021-22881: Fedoraproject Fedora

Medium severity, CVSS 6.1. EPSS: 87.3% chance of exploitation in the next 30 days.

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.

Affected products

• Fedoraproject Fedora: version 33 only
• Rubyonrails Rails: from 6.0.0, before 6.0.3.5 (fixed in 6.0.3.5); from 6.1.0, before 6.1.2.1 (fixed in 6.1.2.1)

Published 2021-02-11. Last modified 2026-06-17.