CVE-2021-22903: Actionpack Possible Open Redirect Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-5hq2-xf89-9jxq
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CVSS 6.1
CWE-601
Published
Advisory Summary

CVE-2021-22903 is a MODERATE (CVSS 6.1) possible open redirect vulnerability vulnerability (CWE-601: URL Redirection to Untrusted Site ('Open Redirect')) affecting Actionpack libraries in the RubyGems ecosystem. The issue involves possible open redirect vulnerability in action pack. Remediation is available by upgrading affected packages to version 6.1.3.2.

CVE-2021-22903 at a Glance

CVE Identifier CVE-2021-22903
GHSA Identifier GHSA-5hq2-xf89-9jxq
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Affected Product Actionpack
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 6.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-22903

To remediate this vulnerability, upgrade all affected Actionpack dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

actionpack fixed: 6.1.3.2 
Upgrade actionpack to 6.1.3.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for actionpack

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-22903, inspect your project dependencies for Actionpack:

inspect dependencies for actionpack

Analyze the terminal output to locate any version of Actionpack in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.1.3.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-601: URL Redirection to Untrusted Site ('Open Redirect'), where the web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect. In Actionpack, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

There is a possible Open Redirect Vulnerability in Action Pack. Versions Affected: >= v6.1.0.rc2 Not affected: < v6.1.0.rc2 Fixed Versions: 6.1.3.2 Impact ------ This is similar to CVE-2021-22881. 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. Since rails/rails@9bc7ea5, strings in config.hosts that do not have a leading dot are converted to regular expressions without proper escaping. This causes, for example, config.hosts << "sub.example.com" to permit a request with a Host header value of sub-example.com. Releases -------- The fixed releases are available at the normal locations. Workarounds ----------- The following monkey patch put in an initializer can be used as a workaround. ```ruby class ActionDispatch::HostAuthorization::Permissions def sanitize_string(host) if host.start_with?(".") /\A(.+\.)?#{Regexp.escape(host[1..-1])}\z/i else /\A#{Regexp.escape host}\z/i end end end ``` Patches ------- To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset. * 6-1-open-redirect.patch - Patch for 6.1 series Please note that only the 6.1.Z, 6.0.Z, and 5.2.Z series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases. Credits ------- Thanks Jonathan Hefner (https://hackerone.com/jonathanhefner) for reporting this bug!

CVE-2021-22903 Affected Actionpack Versions

1 component(s)
Fixed Versions:
6.1.3.2
Product / Package Ecosystem Affected Versions Fixed Version
actionpack
gem/actionpack
RubyGems
≥ 6.1.0.rc2
< 6.1.3.2
6.1.3.2

References

NVD — CVE-2021-22903 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-22903
hackerone.com/reports/1148025 WEB
https://hackerone.com/reports/1148025
discuss.rubyonrails.org/t/cve-2021-22903-po... WEB
https://discuss.rubyonrails.org/t/cve-2021-22903-possible-open-redirect-vulnerability-in-action-pack/77867
Actionpack Release RELEASE
https://github.com/rails/rails/releases/tag/v6.1.3.2
Actionpack Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/CVE-2021-22903.yml
Actionpack Security Information SECURITY
https://groups.google.com/g/rubyonrails-security/c/8TxqXEtgSF0

Frequently Asked Questions

What is CVE-2021-22903?
CVE-2021-22903 is a security vulnerability in Actionpack involving Possible Open Redirect Vulnerability in Action Pack under CWE-601: URL Redirection to Untrusted Site ('Open Redirect').
Which Actionpack versions are affected?
Affected versions include releases prior to 6.1.3.2 across affected packages: actionpack.
What version fixes CVE-2021-22903?
Upgrading to 6.1.3.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is actionpack affected?
Yes, actionpack is affected in releases prior to 6.1.3.2. Upgrade your dependency to 6.1.3.2 or later.
What is the CVSS score of CVE-2021-22903?
CVE-2021-22903 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-22903?
CVE-2021-22903 is classified under CWE-601: URL Redirection to Untrusted Site ('Open Redirect') (The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.).
How can I check RubyGems dependencies for CVE-2021-22903?
Run the dependency tree command: 'inspect dependencies for actionpack'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5hq2-xf89-9jxq",
  "modified" : "2023-08-08T15:56:26Z",
  "published" : "2021-05-05T19:48:29Z",
  "aliases" : [ "CVE-2021-22903" ],
  "summary" : "Possible Open Redirect Vulnerability in Action Pack",
  "details" : "There is a possible Open Redirect Vulnerability in Action Pack.\n\nVersions Affected:  >= v6.1.0.rc2\nNot affected:       < v6.1.0.rc2\nFixed Versions:     6.1.3.2\n\nImpact\n------\nThis is similar to CVE-2021-22881. 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\nwebsite.\n\nSince rails/rails@9bc7ea5, strings in config.hosts that do not have a leading dot are converted to regular expressions without proper escaping. This causes, for example, config.hosts << \"sub.example.com\" to permit a request with a Host header value of sub-example.com.\n\n\nReleases\n--------\nThe fixed releases are available at the normal locations.\n\nWorkarounds\n-----------\nThe following monkey patch put in an initializer can be used as a workaround.\n\n```ruby\nclass ActionDispatch::HostAuthorization::Permissions\n  def sanitize_string(host)\n    if host.start_with?(\".\")\n      /\\A(.+\\.)?#{Regexp.escape(host[1..-1])}\\z/i\n    else\n      /\\A#{Regexp.escape host}\\z/i\n    end\n  end\nend\n```\n\nPatches\n-------\nTo aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.\n\n* 6-1-open-redirect.patch - Patch for 6.1 series\n\nPlease note that only the 6.1.Z, 6.0.Z, and 5.2.Z series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.\n\nCredits\n-------\n\nThanks Jonathan Hefner (https://hackerone.com/jonathanhefner) for reporting this bug!",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "actionpack"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.1.0.rc2"
      }, {
        "fixed" : "6.1.3.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-22903"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/1148025"
  }, {
    "type" : "WEB",
    "url" : "https://discuss.rubyonrails.org/t/cve-2021-22903-possible-open-redirect-vulnerability-in-action-pack/77867"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/releases/tag/v6.1.3.2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/CVE-2021-22903.yml"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/rubyonrails-security/c/8TxqXEtgSF0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-601" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-05T19:47:50Z",
    "nvd_published_at" : "2021-06-11T16:15:00Z"
  }
}