GHSA-2762-657x-v979
MEDIUMAlchemyCMS: Authenticated Remote Code Execution (RCE) via eval injection in ResourcesHelper
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
alchemy_cms💎alchemy_cmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | alchemy_cms | all versions | 7.4.12 |
| 💎RubyGems | alchemy_cms | ≥ 8.0.0.a&&< 8.0.3 | 8.0.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for alchemy_cms. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update alchemy_cms to 7.4.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2762-657x-v979 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2762-657x-v979 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2762-657x-v979. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2762-657x-v979 in your dependencies?
O3 detects GHSA-2762-657x-v979 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.