CVE-2023-28120: Activesupport Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-pj73-v5mw-pm9j
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CVSS 5.3
CWE-79
Published
Advisory Summary

CVE-2023-28120 is a MODERATE (CVSS 5.3) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Activesupport libraries in the RubyGems ecosystem. The issue involves possible xss security vulnerability in safebuffer#bytesplice. Remediation is available by upgrading affected packages to version 7.0.4.3, 6.1.7.3.

CVE-2023-28120 at a Glance

CVE Identifier CVE-2023-28120
GHSA Identifier GHSA-pj73-v5mw-pm9j
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Activesupport
Package Ecosystem RubyGems
Published Date
Last Updated

Security Impact

CVSS: 5.3

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:L/A:N).

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 Low (I:L)
Availability None (A:N)

How to Fix CVE-2023-28120

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

activesupport fixed: 7.0.4.3 
Upgrade activesupport to 7.0.4.3
activesupport fixed: 6.1.7.3 
Upgrade activesupport to 6.1.7.3
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 activesupport

How to Check if You Are Affected

To determine whether your application is affected by CVE-2023-28120, inspect your project dependencies for Activesupport:

inspect dependencies for activesupport

Analyze the terminal output to locate any version of Activesupport in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 7.0.4.3), 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-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 Activesupport, 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 vulnerability in ActiveSupport if the new bytesplice method is called on a SafeBuffer with untrusted user input. This vulnerability has been assigned the CVE identifier CVE-2023-28120. Versions Affected: All. Not affected: None Fixed Versions: 7.0.4.3, 6.1.7.3 # Impact ActiveSupport uses the SafeBuffer string subclass to tag strings as html_safe after they have been sanitized. When these strings are mutated, the tag is should be removed to mark them as no longer being html_safe. Ruby 3.2 introduced a new bytesplice method which ActiveSupport did not yet understand to be a mutation. Users on older versions of Ruby are likely unaffected. All users running an affected release and using bytesplice should either upgrade or use one of the workarounds immediately. # Workarounds Avoid calling bytesplice on a SafeBuffer (html_safe) string with untrusted user input.

CVE-2023-28120 Affected Activesupport Versions

2 component(s)
Fixed Versions:
7.0.4.36.1.7.3
Product / Package Ecosystem Affected Versions Fixed Version
activesupport
gem/activesupport
RubyGems
≥ 7.0.0
< 7.0.4.3
7.0.4.3
activesupport
gem/activesupport
RubyGems
< 6.1.7.3
6.1.7.3

References

NVD — CVE-2023-28120 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-28120
Security Fix Commit FIX COMMIT
https://github.com/rails/rails/commit/3cf23c3f891e2e81c977ea4ab83b62bc2a444b70
Activesupport Security Information SECURITY
https://discuss.rubyonrails.org/t/cve-2023-28120-possible-xss-security-vulnerability-in-safebuffer-bytesplice/82469
Activesupport Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/CVE-2023-28120.yml
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UPV6PVCX4VDJHLFFT42EXBBSGAWZICOW
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZE5W4MH6IE4DV7GELDK6ISCSTFLHKSYO
Activesupport Security Information SECURITY
https://security.netapp.com/advisory/ntap-20240202-0006
Activesupport Security Information SECURITY
https://www.debian.org/security/2023/dsa-5389

Frequently Asked Questions

What is CVE-2023-28120?
CVE-2023-28120 is a security vulnerability in Activesupport involving Possible XSS Security Vulnerability in SafeBuffer#bytesplice under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Activesupport versions are affected?
Affected versions include releases prior to 7.0.4.3, 6.1.7.3 across affected packages: activesupport.
What version fixes CVE-2023-28120?
Upgrading to 7.0.4.3, 6.1.7.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is activesupport affected?
Yes, activesupport is affected in releases prior to 7.0.4.3, 6.1.7.3. Upgrade your dependency to 7.0.4.3, 6.1.7.3 or later.
What is the CVSS score of CVE-2023-28120?
CVE-2023-28120 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2023-28120?
CVE-2023-28120 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-2023-28120?
Run the dependency tree command: 'inspect dependencies for activesupport'. 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-pj73-v5mw-pm9j",
  "modified" : "2025-01-10T18:32:43Z",
  "published" : "2023-03-15T21:36:01Z",
  "aliases" : [ "CVE-2023-28120" ],
  "summary" : "Possible XSS Security Vulnerability in SafeBuffer#bytesplice",
  "details" : "There is a vulnerability in ActiveSupport if the new bytesplice method is called on a SafeBuffer with untrusted user input.\nThis vulnerability has been assigned the CVE identifier CVE-2023-28120.\n\nVersions Affected: All. Not affected: None Fixed Versions: 7.0.4.3, 6.1.7.3\n\n# Impact\n\nActiveSupport uses the SafeBuffer string subclass to tag strings as html_safe after they have been sanitized.\nWhen these strings are mutated, the tag is should be removed to mark them as no longer being html_safe.\n\nRuby 3.2 introduced a new bytesplice method which ActiveSupport did not yet understand to be a mutation.\nUsers on older versions of Ruby are likely unaffected.\n\nAll users running an affected release and using bytesplice should either upgrade or use one of the workarounds immediately.\n\n# Workarounds\n\nAvoid calling bytesplice on a SafeBuffer (html_safe) string with untrusted user input.\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "activesupport"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.0.0"
      }, {
        "fixed" : "7.0.4.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "activesupport"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "6.1.7.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-28120"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails/commit/3cf23c3f891e2e81c977ea4ab83b62bc2a444b70"
  }, {
    "type" : "WEB",
    "url" : "https://discuss.rubyonrails.org/t/cve-2023-28120-possible-xss-security-vulnerability-in-safebuffer-bytesplice/82469"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/CVE-2023-28120.yml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UPV6PVCX4VDJHLFFT42EXBBSGAWZICOW"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZE5W4MH6IE4DV7GELDK6ISCSTFLHKSYO"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20240202-0006"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2023/dsa-5389"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-03-15T21:36:01Z",
    "nvd_published_at" : "2025-01-09T01:15:07Z"
  }
}