CVE-2020-36327: Bundler Dependency Confusion Vulnerability

HIGH
Advisory Identifier: GHSA-fp4w-jxhp-m23p
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CVSS 8.8
Published
Advisory Summary

CVE-2020-36327 is a HIGH (CVSS 8.8) dependency confusion vulnerability (General Security Weakness) affecting Bundler libraries in the RubyGems ecosystem. The issue involves dependency confusion in bundler. Remediation is available by upgrading affected packages to version 2.2.10, 2.2.18.

CVE-2020-36327 at a Glance

CVE Identifier CVE-2020-36327
GHSA Identifier GHSA-fp4w-jxhp-m23p
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification General Security Weakness
Affected Product Bundler
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 8.8

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

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

How to Fix CVE-2020-36327

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

bundler fixed: 2.2.10 
Upgrade bundler to 2.2.10
bundler fixed: 2.2.18 
Upgrade bundler to 2.2.18
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 bundler

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-36327, inspect your project dependencies for Bundler:

inspect dependencies for bundler

Analyze the terminal output to locate any version of Bundler in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.2.10), 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 General Security Weakness. In Bundler, 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

Bundler 1.16.0 through 2.2.9 and 2.2.11 through 2.2.17 sometimes chooses a dependency source based on the highest gem version number, which means that a rogue gem found at a public source may be chosen, even if the intended choice was a private gem that is a dependency of another private gem that is explicitly depended on by the application.

CVE-2020-36327 Affected Bundler Versions

2 component(s)
Fixed Versions:
2.2.102.2.18
Product / Package Ecosystem Affected Versions Fixed Version
bundler
gem/bundler
RubyGems
≥ 1.16.0
< 2.2.10
2.2.10
bundler
gem/bundler
RubyGems
≥ 2.2.11
< 2.2.18
2.2.18

References

NVD — CVE-2020-36327 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-36327
Bundler Source Repository REPOSITORY
https://github.com/rubygems/rubygems/issues/3982
Bundler Source Repository REPOSITORY
https://github.com/rubygems/rubygems/pull/4609
Security Fix Commit FIX COMMIT
https://github.com/rubygems/rubygems/commit/078bf682ac40017b309b5fc69f283ff640e7c129
Bundler Source Repository REPOSITORY
https://github.com/rubygems/rubygems
Bundler Security Information SECURITY
https://bundler.io/blog/2021/02/15/a-more-secure-bundler-we-fixed-our-source-priorities.html
Bundler Source Repository REPOSITORY
https://github.com/rubygems/rubygems/blob/master/bundler/CHANGELOG.md#2218-may-25-2021
Bundler Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/bundler/CVE-2020-36327.yml
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MWXHK5UUHVSHF7HTHMX6JY3WXDVNIHSL
mensfeld.pl/2021/02/rubygems-de... WEB
https://mensfeld.pl/2021/02/rubygems-dependency-confusion-attack-side-of-things
msrc.microsoft.com/update-guide/en-us/... WEB
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24105
www.zofrex.com/blog/2021/04/29/bun... WEB
https://www.zofrex.com/blog/2021/04/29/bundler-still-vulnerable-dependency-confusion-cve-2020-36327

Frequently Asked Questions

What is CVE-2020-36327?
CVE-2020-36327 is a security vulnerability in Bundler involving Dependency Confusion in Bundler under General Security Weakness.
Which Bundler versions are affected?
Affected versions include releases prior to 2.2.10, 2.2.18 across affected packages: bundler.
What version fixes CVE-2020-36327?
Upgrading to 2.2.10, 2.2.18 (or the latest patched release for your respective branch) resolves the vulnerability.
Is bundler affected?
Yes, bundler is affected in releases prior to 2.2.10, 2.2.18. Upgrade your dependency to 2.2.10, 2.2.18 or later.
What is the CVSS score of CVE-2020-36327?
CVE-2020-36327 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2020-36327?
CVE-2020-36327 is classified under General Security Weakness.
How can I check RubyGems dependencies for CVE-2020-36327?
Run the dependency tree command: 'inspect dependencies for bundler'. 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-fp4w-jxhp-m23p",
  "modified" : "2021-08-31T21:03:58Z",
  "published" : "2021-05-24T18:12:33Z",
  "aliases" : [ "CVE-2020-36327" ],
  "summary" : "Dependency Confusion in Bundler",
  "details" : "Bundler 1.16.0 through 2.2.9 and 2.2.11 through 2.2.17 sometimes chooses a dependency source based on the highest gem version number, which means that a rogue gem found at a public source may be chosen, even if the intended choice was a private gem that is a dependency of another private gem that is explicitly depended on by the application.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "bundler"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.16.0"
      }, {
        "fixed" : "2.2.10"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "bundler"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.2.11"
      }, {
        "fixed" : "2.2.18"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-36327"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubygems/rubygems/issues/3982"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubygems/rubygems/pull/4609"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubygems/rubygems/commit/078bf682ac40017b309b5fc69f283ff640e7c129"
  }, {
    "type" : "WEB",
    "url" : "https://bundler.io/blog/2021/02/15/a-more-secure-bundler-we-fixed-our-source-priorities.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rubygems/rubygems"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubygems/rubygems/blob/master/bundler/CHANGELOG.md#2218-may-25-2021"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/bundler/CVE-2020-36327.yml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MWXHK5UUHVSHF7HTHMX6JY3WXDVNIHSL"
  }, {
    "type" : "WEB",
    "url" : "https://mensfeld.pl/2021/02/rubygems-dependency-confusion-attack-side-of-things"
  }, {
    "type" : "WEB",
    "url" : "https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-24105"
  }, {
    "type" : "WEB",
    "url" : "https://www.zofrex.com/blog/2021/04/29/bundler-still-vulnerable-dependency-confusion-cve-2020-36327"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-20T21:48:14Z",
    "nvd_published_at" : "2021-04-29T03:15:00Z"
  }
}