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Fencer Vulns
medium 6.1

CVE-2021-22881 json

Actionpack Open Redirect Vulnerability

published 2021-02-11 5 y ago modified 2026-06-17 4 mo ago also GHSA-8877-prq4-9xfw , EUVD-2021-0631

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
87.3%
EPSS 87.3% chance of exploitation in 30 days, percentile 99.7%
public exploits
0
none known, plus a Nuclei check

Summary

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.

Patch / fix

  • rubygems actionpack 6.0.3.5, 6.1.2.1
  • rubyonrails rails 6.0.3.5, 6.1.2.1
  • rails Debian 14, Debian 13, Debian 12 2:6.0.3.5+dfsg-1

debian advisories DEBIAN-CVE-2021-22881

  • rubygem-actionpack-6.0 openSUSE Tumbleweed 6.0.4.4-1.1

opensuse advisories openSUSE-SU-2024:11821-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-22881 updated cvss 6.1

rubygem-actionpack: open redirect vulnerability may lead to confidentiality and integrity compromise

  • Red Hat CloudForms Management Engine 5 cfme-gemset
    affected: no fix planned “Will not fix”
  • Red Hat Satellite 6 tfm-rubygem-actionpack, tfm-ror52-rubygem-actionpack
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

87.30% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Ruby on Rails - Open Redirect via Host Header Injection nuclei detection template
  • hackerone.com https://hackerone.com/reports/1047447 referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com http://www.openwall.com/lists/oss-security/2021/12/14/5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:P/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
rubygems actionpack
>=6.0.0, <6.0.3.5
>=6.1.0, <6.1.2.1
6.0.3.5
6.1.2.1

Affected products

  • n/a https://github.com/rails/rails

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.