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CVE-2025-27407: Schema to Shell: The GraphQL-Ruby Introspection Nightmare

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Schema to Shell: The GraphQL-Ruby Introspection Nightmare

Vulnerability ID: CVE-2025-27407
CVSS Score: 9.1
Published: 2025-03-12

A critical RCE in the popular graphql-ruby gem allows attackers to achieve remote code execution by providing malicious introspection data. By leveraging unsafe metaprogramming, specifically string-based class_eval, an attacker can inject arbitrary Ruby code during schema reconstruction.

TL;DR

If your Ruby application loads GraphQL schemas from untrusted sources (like user uploads or external endpoints), you are likely vulnerable to RCE. The graphql-ruby gem was building code strings from schema names without validation. Update to the latest patch versions immediately.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-94 (Code Injection)
  • CVSS v3.1: 9.1 (Critical)
  • Attack Vector: Network (Introspection Loading)
  • EPSS Score: 5.86% (High Probability)
  • Impact: Remote Code Execution (RCE)
  • Exploit Status: PoC Available

Affected Systems

  • graphql-ruby gem < 2.4.13
  • GitLab < 17.9.2
  • Applications using GraphQL::Client with untrusted endpoints
  • Any Ruby app loading introspection data via from_introspection
  • graphql-ruby: < 2.4.13 (Fixed in: 2.4.13)
  • graphql-ruby: < 2.3.21 (Fixed in: 2.3.21)
  • GitLab Community/Enterprise: 17.7.0 - 17.7.6 (Fixed in: 17.7.7)
  • GitLab Community/Enterprise: 17.8.0 - 17.8.4 (Fixed in: 17.8.5)

Code Analysis

Commit: e58676c

Fix for CVE-2025-27407: Replace string eval with define_method

- class_eval <<-RUBY
- def #{method_name}
+ define_method(method_name) do
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Exploit Details

Mitigation Strategies

  • Upgrade graphql-ruby to the latest patch release immediately.
  • Isolate schema loading mechanisms to trusted administrative contexts only.
  • Implement strict input validation on any JSON uploaded for schema introspection.

Remediation Steps:

  1. Check current version: bundle list | grep graphql
  2. Update gem: bundle update graphql
  3. Verify version matches patched release (e.g., 2.4.13+)
  4. Restart application services.

References

Read the full report for CVE-2025-27407 on our website for more details including interactive diagrams and full exploit analysis.

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