Comprehensive Technical Analysis of EUVD-2026-3590 (CVE-2026-23947)

Orval Arbitrary Code Execution via Untrusted OpenAPI Specifications

1. Vulnerability Assessment and Severity Evaluation

Vulnerability Overview

EUVD-2026-3590 (CVE-2026-23947) is a critical arbitrary code execution (ACE) vulnerability in Orval, a popular TypeScript client generator for OpenAPI/Swagger specifications. The flaw allows attackers to inject malicious TypeScript/JavaScript code into generated clients via the x-enumDescriptions field in an OpenAPI specification, which is improperly escaped during getEnumImplementation().

This vulnerability is distinct from CVE-2026-22785, which addressed a similar issue in a different code path. The new flaw demonstrates that incomplete fixes in security patches can lead to residual attack surfaces.

CVSS v4.0 Severity Analysis

Metric	Value	Explanation
Base Score	9.3 (Critical)	High impact on confidentiality, integrity, and availability.
Attack Vector (AV)	Network (N)	Exploitable remotely via crafted OpenAPI specs.
Attack Complexity (AC)	Low (L)	No special conditions required.
Attack Requirements (AT)	None (N)	No prior access or privileges needed.
Privileges Required (PR)	None (N)	No authentication required.
User Interaction (UI)	None (N)	Exploitation does not require user action.
Vulnerable Component (VC)	High (H)	Full compromise of generated client code.
Integrity Impact (VI)	High (H)	Malicious code execution alters application logic.
Availability Impact (VA)	High (H)	Potential for denial-of-service or further exploitation.
Subsequent Confidentiality (SC)	None (N)	No direct impact on downstream systems.
Subsequent Integrity (SI)	None (N)	No lateral movement implications.
Subsequent Availability (SA)	None (N)	No cascading availability impact.

Key Takeaways:

• Critical severity (9.3) due to remote, unauthenticated code execution.
• Low attack complexity makes it highly exploitable.
• No user interaction required, increasing risk in CI/CD pipelines and automated workflows.

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2. Potential Attack Vectors and Exploitation Methods

Exploitation Mechanism

1. Attacker-Controlled OpenAPI Specification

   • An attacker crafts a malicious OpenAPI (v3) or Swagger (v2) specification containing a malicious x-enumDescriptions field.
   • Example payload:

     components:
       schemas:
         MaliciousEnum:
           type: string
           enum: ["SAFE_VALUE"]
           x-enumDescriptions:
             SAFE_VALUE: "*/ console.log('Arbitrary Code Execution'); //"
     

   • When processed by Orval, the getEnumImplementation() function fails to escape the injected code, embedding it in the generated TypeScript client.

2. Code Injection in Generated Client

   • Orval generates a TypeScript enum with the malicious payload:

     export const enum MaliciousEnum {
       SAFE_VALUE = "SAFE_VALUE" /* console.log('Arbitrary Code Execution'); // */,
     }
     

   • When the generated client is compiled or executed, the injected code runs in the context of the application.

3. Exploitation Scenarios

   • CI/CD Pipeline Poisoning: Attackers submit a malicious OpenAPI spec to a repository, leading to code execution during automated client generation.
   • Supply Chain Attacks: Compromised OpenAPI specs in public registries (e.g., SwaggerHub) can propagate malicious clients.
   • Developer Workstations: Local execution of Orval on untrusted specs can lead to arbitrary code execution.

Proof of Concept (PoC)

A minimal PoC demonstrating the vulnerability:

# malicious-spec.yaml
openapi: 3.0.0
info:
  title: Malicious API
  version: 1.0.0
paths: {}
components:
  schemas:
    ExploitEnum:
      type: string
      enum: ["TRIGGER"]
      x-enumDescriptions:
        TRIGGER: "*/ process.exit(1); //"

Running:

npx orval --input malicious-spec.yaml --output client.ts

Results in:

// client.ts
export const enum ExploitEnum {
  TRIGGER = "TRIGGER" /* process.exit(1); // */,
}

When imported and used, process.exit(1) executes.

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3. Affected Systems and Software Versions

Vulnerable Versions

• Orval versions 7.10.0 to < 8.0.2
• All environments consuming Orval-generated TypeScript clients (Node.js, browser, Deno, etc.).

Scope of Impact

• Direct Impact: Applications using Orval to generate clients from untrusted OpenAPI specs.
• Indirect Impact: Downstream projects depending on vulnerable generated clients.
• CI/CD Systems: Automated pipelines processing OpenAPI specs are at high risk.

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4. Recommended Mitigation Strategies

Immediate Actions

1. Upgrade Orval

   • Patch to Orval v8.0.2 or later (fixes the x-enumDescriptions injection flaw).
   • Verify the fix by testing with a malicious OpenAPI spec.

2. Input Validation & Sanitization

   • Pre-process OpenAPI specs to strip or escape x-enumDescriptions and other extensible fields.
   • Use tools like Spectral or OpenAPI linting to detect suspicious patterns.

3. Runtime Protections

   • Sandbox generated clients in isolated environments (e.g., Docker containers, VMs).
   • Use Content Security Policy (CSP) in web applications to mitigate script execution.

4. CI/CD Hardening

   • Restrict OpenAPI spec sources to trusted repositories.
   • Scan specs for malicious patterns before processing (e.g., using custom regex or static analysis).
   • Sign and verify OpenAPI specs using cryptographic hashes.

Long-Term Recommendations

• Adopt a Zero-Trust Approach for OpenAPI specs in development pipelines.
• Monitor for suspicious enum patterns in generated code (e.g., /*, //, eval, require).
• Integrate SAST/DAST tools (e.g., SonarQube, Snyk) to detect code injection in generated clients.
• Educate developers on the risks of untrusted OpenAPI specs.

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5. Impact on the European Cybersecurity Landscape

Regulatory and Compliance Implications

• NIS2 Directive (EU 2022/2555): Organizations in critical sectors (energy, healthcare, finance) must ensure secure software supply chains. This vulnerability could lead to non-compliance if unpatched.
• GDPR (Art. 32): Failure to mitigate ACE vulnerabilities may result in data breaches, triggering reporting obligations and fines.
• EU Cyber Resilience Act (CRA): Mandates vulnerability disclosure and patching. Orval’s maintainers must ensure timely fixes to avoid penalties.

Sector-Specific Risks

Sector	Risk Scenario	Potential Impact
Financial Services	Malicious OpenAPI spec in a banking API client	Fraud, data exfiltration, transaction manipulation
Healthcare	Compromised FHIR/OpenAPI spec in a hospital system	Patient data theft, ransomware deployment
Critical Infrastructure	Injected code in SCADA/IoT API clients	Operational disruption, physical damage
Government	Supply chain attack via a public API registry	Espionage, service disruption

Broader Implications

• Supply Chain Attacks: Orval is widely used in European tech stacks (e.g., fintech, e-government). A single compromised spec could affect thousands of downstream applications.
• Trust in OpenAPI Ecosystem: This vulnerability undermines confidence in OpenAPI as a secure specification format, potentially slowing adoption in regulated industries.
• Incident Response Challenges: Detecting and remediating injected code in generated clients requires deep static analysis, increasing SOC workload.

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6. Technical Details for Security Professionals

Root Cause Analysis

• Vulnerable Code Path: @orval/core/src/core/getEnumImplementation.ts
  • The function fails to escape x-enumDescriptions when generating TypeScript enums.
  • Example vulnerable snippet:

    const enumDescription = enumValue['x-enumDescriptions']?.[value];
    // Missing sanitization before embedding in template
    return `${value} = "${value}"${enumDescription ? ` /* ${enumDescription} */` : ''}`;
    

• Exploitation Primitive: The /* ... */ comment syntax in TypeScript allows arbitrary code execution when the enum is referenced.

Detection Methods

1. Static Analysis

   • Search generated clients for:

     /\/\*.*?(eval|require|process\.|import|console\.log).*?\*\//
     

   • Use TypeScript compiler API to detect unsafe enum patterns.

2. Dynamic Analysis

   • Execute generated clients in a sandboxed environment (e.g., Node.js --unhandled-rejections=strict).
   • Monitor for unexpected process spawning or network calls.

3. OpenAPI Spec Analysis

   • Scan for suspicious x-enumDescriptions fields:

     x-enumDescriptions:
       SAFE_VALUE: "*/ malicious_code(); //"
     

Forensic Investigation

• Log Analysis: Check CI/CD logs for unusual OpenAPI spec sources.
• Git History: Review recent changes to OpenAPI specs for injected fields.
• Memory Forensics: If exploitation is suspected, analyze process memory for injected payloads.

Advanced Mitigation Techniques

• Custom Orval Plugin: Override getEnumImplementation() to sanitize x-enumDescriptions.
• Post-Generation Hooks: Use Babel/TypeScript transformers to remove unsafe comments.
• Immutable Builds: Store hashes of generated clients to detect tampering.

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Conclusion

EUVD-2026-3590 (CVE-2026-23947) is a critical arbitrary code execution vulnerability in Orval that poses significant risks to European organizations, particularly in regulated sectors. The flaw highlights the dangers of incomplete security patches and the need for rigorous input validation in code generation tools.

Key Recommendations: ✅ Upgrade to Orval v8.0.2 immediately. ✅ Sanitize OpenAPI specs before processing. ✅ Monitor generated clients for malicious patterns. ✅ Harden CI/CD pipelines against supply chain attacks.

Failure to address this vulnerability could lead to data breaches, regulatory penalties, and operational disruptions across the EU’s digital infrastructure. Security teams should prioritize patching and implement compensating controls while awaiting vendor fixes.