CVE-2024-29034

CarrierWave content-Type allowlist bypass vulnerability which possibly leads to XSS remained

# For CarrierWave 3.x
CarrierWave::SanitizedFile.class_eval do
  def declared_content_type
    @declared_content_type ||
      if @file.respond_to?(:content_type) && @file.content_type
        Marcel::MimeType.for(declared_type: @file.content_type.to_s.chomp)
      end
  end
end

# For CarrierWave 2.x
CarrierWave::SanitizedFile.class_eval do
  def existing_content_type
    if @file.respond_to?(:content_type) && @file.content_type
      Marcel::MimeType.for(declared_type: @file.content_type.to_s.chomp)
    end
  end
end

The vulnerability CVE-2023-49090 wasn't fully addressed.

This vulnerability is caused by the fact that when uploading to object storage, including Amazon S3, it is possible to set a Content-Type value that is interpreted by browsers to be different from what's allowed by content_type_allowlist, by providing multiple values separated by commas.

This bypassed value can be used to cause XSS.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2024-29034 has a CVSS score of 6.8 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.0.7, 2.2.6); upgrading removes the vulnerable code path.

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1. What is CVE-2024-29034? CVE-2024-29034 is a medium-severity cross-site scripting (XSS) vulnerability in carrierwave (rubygems), affecting versions >= 3.0.0, < 3.0.7. It is fixed in 3.0.7, 2.2.6. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2024-29034? CVE-2024-29034 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of carrierwave are affected by CVE-2024-29034? carrierwave (rubygems) versions >= 3.0.0, < 3.0.7 is affected.
4. Is there a fix for CVE-2024-29034? Yes. CVE-2024-29034 is fixed in 3.0.7, 2.2.6. Upgrade to this version or later.
5. Is CVE-2024-29034 exploitable, and should I be worried? Whether CVE-2024-29034 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2024-29034 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2024-29034?
   • Upgrade carrierwave to 3.0.7 or later
   • Upgrade carrierwave to 2.2.6 or later

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