CVE-2018-3741: Rails html sanitizer Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-px3r-jm9g-c8w8
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2018-3741 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Rails html sanitizer libraries in the RubyGems ecosystem. The issue involves rails-html-sanitizer cross-site scripting vulnerability. Remediation is available by upgrading affected packages to version 1.0.4.

CVE-2018-3741 at a Glance

CVE Identifier CVE-2018-3741
GHSA Identifier GHSA-px3r-jm9g-c8w8
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 Rails html sanitizer
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-2018-3741

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

rails-html-sanitizer fixed: 1.0.4 
Upgrade rails-html-sanitizer to 1.0.4
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 rails-html-sanitizer

How to Check if You Are Affected

To determine whether your application is affected by CVE-2018-3741, inspect your project dependencies for Rails html sanitizer:

inspect dependencies for rails-html-sanitizer

Analyze the terminal output to locate any version of Rails html sanitizer in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.4), 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 Rails html sanitizer, 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 possible XSS vulnerability in all rails-html-sanitizer gem versions below 1.0.4 for Ruby. The gem allows non-whitelisted attributes to be present in sanitized output when input with specially-crafted HTML fragments, and these attributes can lead to an XSS attack on target applications. This issue is similar to CVE-2018-8048 in Loofah. All users running an affected release should either upgrade or use one of the workarounds immediately.

CVE-2018-3741 Affected Rails html sanitizer Versions

1 component(s)
Fixed Versions:
1.0.4
Product / Package Ecosystem Affected Versions Fixed Version
rails-html-sanitizer
gem/rails-html-sanitizer
RubyGems
< 1.0.4
1.0.4

References

NVD — CVE-2018-3741 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-3741
Security Fix Commit FIX COMMIT
https://github.com/rails/rails-html-sanitizer/commit/f3ba1a839a35f2ba7f941c15e239a1cb379d56ae
Rails html sanitizer Source Repository REPOSITORY
https://github.com/rails/rails-html-sanitizer

Frequently Asked Questions

What is CVE-2018-3741?
CVE-2018-3741 is a security vulnerability in Rails html sanitizer involving rails-html-sanitizer Cross-site Scripting vulnerability under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Rails html sanitizer versions are affected?
Affected versions include releases prior to 1.0.4 across affected packages: rails-html-sanitizer.
What version fixes CVE-2018-3741?
Upgrading to 1.0.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is rails-html-sanitizer affected?
Yes, rails-html-sanitizer is affected in releases prior to 1.0.4. Upgrade your dependency to 1.0.4 or later.
What is the CVSS score of CVE-2018-3741?
CVE-2018-3741 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-2018-3741?
CVE-2018-3741 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-2018-3741?
Run the dependency tree command: 'inspect dependencies for rails-html-sanitizer'. 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-px3r-jm9g-c8w8",
  "modified" : "2023-03-01T18:54:07Z",
  "published" : "2018-04-26T15:41:10Z",
  "aliases" : [ "CVE-2018-3741" ],
  "summary" : "rails-html-sanitizer Cross-site Scripting vulnerability",
  "details" : "There is a possible XSS vulnerability in all rails-html-sanitizer gem versions below 1.0.4 for Ruby. The gem allows non-whitelisted attributes to be present in sanitized output when input with specially-crafted HTML fragments, and these attributes can lead to an XSS attack on target applications. This issue is similar to CVE-2018-8048 in Loofah. All users running an affected release should either upgrade or use one of the workarounds immediately.",
  "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" : "rails-html-sanitizer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-3741"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails-html-sanitizer/commit/f3ba1a839a35f2ba7f941c15e239a1cb379d56ae"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rails/rails-html-sanitizer"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T21:50:14Z",
    "nvd_published_at" : "2018-03-30T19:29:00Z"
  }
}