CVE-2021-22902: Actionpack Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-g8ww-46x2-2p65
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CVSS 7.5
CWE-400
Published
Advisory Summary

CVE-2021-22902 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Actionpack libraries in the RubyGems ecosystem. The issue involves denial of service in action dispatch. Remediation is available by upgrading affected packages to version 6.0.3.7, 6.1.3.2.

CVE-2021-22902 at a Glance

CVE Identifier CVE-2021-22902
GHSA Identifier GHSA-g8ww-46x2-2p65
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Actionpack
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:N/S:U/C:N/I:N/A:H).

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

How to Fix CVE-2021-22902

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: 6.0.3.7 
Upgrade actionpack to 6.0.3.7
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-2021-22902, 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 6.0.3.7), 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-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. 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

Impact ------ There is a possible Denial of Service vulnerability in Action Dispatch. Carefully crafted Accept headers can cause the mime type parser in Action Dispatch to do catastrophic backtracking in the regular expression engine. Releases -------- The fixed releases are available at the normal locations. Workarounds ----------- The following monkey patch placed in an initializer can be used to work around the issue. ```ruby module Mime class Type MIME_REGEXP = /\A(?:\*\/\*|#{MIME_NAME}\/(?:\*|#{MIME_NAME})(?>\s*#{MIME_PARAMETER}\s*)*)\z/ 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. * 6-0-Prevent-catastrophic-backtracking-during-mime-parsin.patch - Patch for 6.0 series * 6-1-Prevent-catastrophic-backtracking-during-mime-parsin.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 to Security Curious <security...@pm.me> for reporting this!

CVE-2021-22902 Affected Actionpack Versions

2 component(s)
Fixed Versions:
6.0.3.76.1.3.2
Product / Package Ecosystem Affected Versions Fixed Version
actionpack
gem/actionpack
RubyGems
≥ 6.0.0
< 6.0.3.7
6.0.3.7
actionpack
gem/actionpack
RubyGems
≥ 6.1.0
< 6.1.3.2
6.1.3.2

References

NVD — CVE-2021-22902 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-22902
hackerone.com/reports/1138654 WEB
https://hackerone.com/reports/1138654
discuss.rubyonrails.org/t/cve-2021-22902-po... WEB
https://discuss.rubyonrails.org/t/cve-2021-22902-possible-denial-of-service-vulnerability-in-action-dispatch/77866
Actionpack Release RELEASE
https://github.com/rails/rails/releases/tag/v6.0.3.7
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-2021-22902.yml
Actionpack Security Information SECURITY
https://groups.google.com/g/rubyonrails-security/c/_5ID_ld9u1c

Frequently Asked Questions

What is CVE-2021-22902?
CVE-2021-22902 is a security vulnerability in Actionpack involving Denial of Service in Action Dispatch under CWE-400: Uncontrolled Resource Consumption.
Which Actionpack versions are affected?
Affected versions include releases prior to 6.0.3.7, 6.1.3.2 across affected packages: actionpack.
What version fixes CVE-2021-22902?
Upgrading to 6.0.3.7, 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 6.0.3.7, 6.1.3.2. Upgrade your dependency to 6.0.3.7, 6.1.3.2 or later.
What is the CVSS score of CVE-2021-22902?
CVE-2021-22902 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2021-22902?
CVE-2021-22902 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check RubyGems dependencies for CVE-2021-22902?
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-g8ww-46x2-2p65",
  "modified" : "2023-08-08T15:37:20Z",
  "published" : "2021-05-05T19:48:21Z",
  "aliases" : [ "CVE-2021-22902" ],
  "summary" : "Denial of Service in Action Dispatch",
  "details" : "Impact\n------\nThere is a possible Denial of Service vulnerability in Action Dispatch. Carefully crafted Accept headers can cause the mime type parser in Action Dispatch to do catastrophic backtracking in the regular expression engine.\n\nReleases\n--------\nThe fixed releases are available at the normal locations.\n\nWorkarounds\n-----------\nThe following monkey patch placed in an initializer can be used to work around the issue.\n\n```ruby\nmodule Mime\n  class Type\n    MIME_REGEXP = /\\A(?:\\*\\/\\*|#{MIME_NAME}\\/(?:\\*|#{MIME_NAME})(?>\\s*#{MIME_PARAMETER}\\s*)*)\\z/\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* 6-0-Prevent-catastrophic-backtracking-during-mime-parsin.patch - Patch for 6.0 series\n* 6-1-Prevent-catastrophic-backtracking-during-mime-parsin.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 to Security Curious <security...@pm.me> for reporting this!",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "actionpack"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.0.0"
      }, {
        "fixed" : "6.0.3.7"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 6.0.3.6"
    }
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "actionpack"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.1.0"
      }, {
        "fixed" : "6.1.3.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 6.1.3.1"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-22902"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/1138654"
  }, {
    "type" : "WEB",
    "url" : "https://discuss.rubyonrails.org/t/cve-2021-22902-possible-denial-of-service-vulnerability-in-action-dispatch/77866"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/releases/tag/v6.0.3.7"
  }, {
    "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-2021-22902.yml"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/rubyonrails-security/c/_5ID_ld9u1c"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-05T19:47:37Z",
    "nvd_published_at" : "2021-06-11T16:15:00Z"
  }
}