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Vulnerabilities

Vulnerability · 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.

Published Feb 11, 2021 · catalog updated Jun 17, 2026 · The Host Authorization middleware

Last checked Nov 8, 2026. A connected source was read within the last 7 days.

Check this week

CVE-2021-22881 is not in CISA KEV. FIRST estimates a 87.30% chance of exploitation in the next 30 days. Check whether you run The Host Authorization middleware.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (The Host Authorization middleware).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium6.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
87.30%
Remediation
Version ranges on file
Affected products
cpe fedoraproject/fedora · cpe rubyonrails/rails

The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability. Specially crafted 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 header can be used to redirect to a malicious website.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe fedoraproject/fedora33
  • cpe rubyonrails/rails< 6.0.3.5
  • cpe rubyonrails/rails< 6.1.2.1

How to fix CVE-2021-22881

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-22881 is not in CISA KEV. FIRST estimates a 87.30% chance of exploitation in the next 30 days. Check whether you run The Host Authorization middleware.

Which versions are affected?

Compare what you have installed with 33, < 6.0.3.5, < 6.1.2.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-601: URL Redirection to Untrusted Site (Open Redirect). EPSS 87.30%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ruby on Rails security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 11, 2021 · Monitored products — high

    Detected

    The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability. Specially crafted 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 leadin

  2. Jun 17, 2026 · Monitored products — high

    Updated

    The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability. Specially crafted 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 leadin

Sources

  • CVE.orgVulnerability recordCVE-2021-22881

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2021-22881

    The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability. Specially crafted 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 leadin

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 8, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 8, 2026
  • Monitored products — highNov 8, 2026