CVE-2020-8161: Directory traversal in Rack :Directory App Bundled With Rack Vulnerability

HIGH
Advisory Identifier: GHSA-5f9h-9pjv-v6j7
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CVSS 8.6
CWE-548 CWE-22
Published
Advisory Summary

CVE-2020-8161 is a HIGH (CVSS 8.6) :directory app bundled with rack vulnerability (CWE-548: Exposure of Information Through Directory Listing) affecting Directory traversal in Rack libraries in the RubyGems ecosystem. The issue involves :directory app bundled with rack. Remediation is available by upgrading affected packages to version 2.1.3.

CVE-2020-8161 at a Glance

CVE Identifier CVE-2020-8161
GHSA Identifier GHSA-5f9h-9pjv-v6j7
Severity HIGH
CVSS v3.1 Base Score 8.6
CWE Classification CWE-548: Exposure of Information Through Directory Listing
Affected Product Directory traversal in Rack
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 8.6

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

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

How to Fix CVE-2020-8161

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

rack fixed: 2.1.3 
Upgrade rack to 2.1.3
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 rack

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-8161, inspect your project dependencies for Directory traversal in Rack:

inspect dependencies for rack

Analyze the terminal output to locate any version of Directory traversal in Rack in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.1.3), 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-548: Exposure of Information Through Directory Listing, where the product inappropriately exposes a directory listing with an index of all the resources located inside of the directory. In Directory traversal in Rack, 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

A directory traversal vulnerability exists in rack < 2.2.0 that allows an attacker perform directory traversal vulnerability in the Rack::Directory app that is bundled with Rack which could result in information disclosure.

CVE-2020-8161 Affected Directory traversal in Rack Versions

1 component(s)
Fixed Versions:
2.1.3
Product / Package Ecosystem Affected Versions Fixed Version
rack
gem/rack
RubyGems
< 2.1.3
2.1.3

References

NVD — CVE-2020-8161 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-8161
Security Fix Commit FIX COMMIT
https://github.com/rack/rack/commit/dddb7ad18ed79ca6ab06ccc417a169fde451246e
Directory traversal in Rack Source Repository REPOSITORY
https://github.com/rack/rack
Directory traversal in Rack Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2020-8161.yml
groups.google.com/forum/ WEB
https://groups.google.com/forum/#!topic/ruby-security-ann/T4ZIsfRf2eA
Directory traversal in Rack Security Information SECURITY
https://groups.google.com/g/rubyonrails-security/c/IOO1vNZTzPA
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2020/07/msg00006.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2023/01/msg00038.html
usn.ubuntu.com/4561-1 WEB
https://usn.ubuntu.com/4561-1

Frequently Asked Questions

What is CVE-2020-8161?
CVE-2020-8161 is a security vulnerability in Directory traversal in Rack involving :Directory app bundled with Rack under CWE-548: Exposure of Information Through Directory Listing.
Which Directory traversal in Rack versions are affected?
Affected versions include releases prior to 2.1.3 across affected packages: rack.
What version fixes CVE-2020-8161?
Upgrading to 2.1.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is rack affected?
Yes, rack is affected in releases prior to 2.1.3. Upgrade your dependency to 2.1.3 or later.
What is the CVSS score of CVE-2020-8161?
CVE-2020-8161 has a CVSS v3.1 base score of 8.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N.
What CWE is associated with CVE-2020-8161?
CVE-2020-8161 is classified under CWE-548: Exposure of Information Through Directory Listing (The product inappropriately exposes a directory listing with an index of all the resources located inside of the directory.).
How can I check RubyGems dependencies for CVE-2020-8161?
Run the dependency tree command: 'inspect dependencies for rack'. 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-5f9h-9pjv-v6j7",
  "modified" : "2022-05-26T20:45:56Z",
  "published" : "2020-07-06T21:31:02Z",
  "aliases" : [ "CVE-2020-8161" ],
  "summary" : "Directory traversal in Rack::Directory app bundled with Rack",
  "details" : "A directory traversal vulnerability exists in rack < 2.2.0 that allows an attacker perform directory traversal vulnerability in the Rack::Directory app that is bundled with Rack which could result in information disclosure.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "rack"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.1.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-8161"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rack/rack/commit/dddb7ad18ed79ca6ab06ccc417a169fde451246e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rack/rack"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2020-8161.yml"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/forum/#!topic/ruby-security-ann/T4ZIsfRf2eA"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/rubyonrails-security/c/IOO1vNZTzPA"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/07/msg00006.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2023/01/msg00038.html"
  }, {
    "type" : "WEB",
    "url" : "https://usn.ubuntu.com/4561-1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22", "CWE-548" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-07-06T21:30:32Z",
    "nvd_published_at" : "2020-07-02T19:15:00Z"
  }
}