CVE-2020-8264: Actionpack Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-35mm-cc6r-8fjp
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2020-8264 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Actionpack libraries in the RubyGems ecosystem. The issue involves cross-site scripting in actionpack. Remediation is available by upgrading affected packages to version 6.0.3.4.

CVE-2020-8264 at a Glance

CVE Identifier CVE-2020-8264
GHSA Identifier GHSA-35mm-cc6r-8fjp
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
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-2020-8264

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: 6.0.3.4 
Upgrade actionpack to 6.0.3.4
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-2020-8264, 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 6.0.3.4), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. 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

In actionpack gem >= 6.0.0, a possible XSS vulnerability exists when an application is running in development mode allowing an attacker to send or embed (in another page) a specially crafted URL which can allow the attacker to execute JavaScript in the context of the local application. This vulnerability is in the Actionable Exceptions middleware. Workarounds ----------- Until such time as the patch can be applied, application developers should disable the Actionable Exceptions middleware in their development environment via a line such as this one in their config/environment/development.rb: `config.middleware.delete ActionDispatch::ActionableExceptions`

CVE-2020-8264 Affected Actionpack Versions

1 component(s)
Fixed Versions:
6.0.3.4
Product / Package Ecosystem Affected Versions Fixed Version
actionpack
gem/actionpack
RubyGems
≥ 6.0.0
< 6.0.3.4
6.0.3.4

References

NVD — CVE-2020-8264 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-8264
hackerone.com/reports/904059 WEB
https://hackerone.com/reports/904059
Actionpack Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/CVE-2020-8264.yml
Actionpack Security Information SECURITY
https://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk
Actionpack Security Information SECURITY
https://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk/m/oJWw-xhNAQAJ

Frequently Asked Questions

What is CVE-2020-8264?
CVE-2020-8264 is a security vulnerability in Actionpack involving Cross-site scripting in actionpack under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Actionpack versions are affected?
Affected versions include releases prior to 6.0.3.4 across affected packages: actionpack.
What version fixes CVE-2020-8264?
Upgrading to 6.0.3.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is actionpack affected?
Yes, actionpack is affected in releases prior to 6.0.3.4. Upgrade your dependency to 6.0.3.4 or later.
What is the CVSS score of CVE-2020-8264?
CVE-2020-8264 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-2020-8264?
CVE-2020-8264 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check RubyGems dependencies for CVE-2020-8264?
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-35mm-cc6r-8fjp",
  "modified" : "2023-08-08T15:34:06Z",
  "published" : "2021-04-07T20:58:47Z",
  "aliases" : [ "CVE-2020-8264" ],
  "summary" : "Cross-site scripting in actionpack",
  "details" : "In actionpack gem >= 6.0.0, a possible XSS vulnerability exists when an application is running in development mode allowing an attacker to send or embed (in another page) a specially crafted URL which can allow the attacker to execute JavaScript in the context of the local application. This vulnerability is in the Actionable Exceptions middleware.\n\nWorkarounds\n-----------\nUntil such time as the patch can be applied, application developers should disable the Actionable Exceptions middleware in their development environment via a line such as this one in their config/environment/development.rb: `config.middleware.delete ActionDispatch::ActionableExceptions`",
  "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" : "6.0.0"
      }, {
        "fixed" : "6.0.3.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 6.0.3.3"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-8264"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/904059"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/CVE-2020-8264.yml"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/rubyonrails-security/c/yQzUVfv42jk/m/oJWw-xhNAQAJ"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-06T23:19:13Z",
    "nvd_published_at" : "2021-01-06T21:15:00Z"
  }
}