EUVD-2025-202180

Comprehensive Technical Analysis of EUVD-2025-202180

1. Vulnerability Assessment and Severity Evaluation

Vulnerability Description: The vulnerability in question is a prototype pollution issue in the Elysia framework, specifically within the mergeDeep function. This occurs when merging results of two standard schema validations with the same key, allowing the __proto__ property to be manipulated. When combined with another vulnerability (GHSA-8vch-m3f4-q8jf), this can lead to Remote Code Execution (RCE).

Severity Evaluation:

• Base Score: 9.1 (CVSS 4.0)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

The high base score indicates a critical vulnerability due to the potential for RCE, which can have severe impacts on confidentiality and integrity. The attack vector is network-based (AV:N), requires low complexity (AC:L), and does not require user interaction (UI:N). The vulnerability can be exploited by an attacker with no privileges (PR:N) and has high impacts on confidentiality and integrity (VC:H, VI:H).

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Prototype Pollution: An attacker can manipulate the __proto__ property during the merging process, leading to the injection of malicious code.
• Combination with GHSA-8vch-m3f4-q8jf: When combined with another vulnerability, this can escalate to RCE, allowing the attacker to execute arbitrary code on the server.

Exploitation Methods:

• Crafted Input: An attacker can send specially crafted input to the server, exploiting the prototype pollution vulnerability.
• Chained Exploits: By chaining this vulnerability with GHSA-8vch-m3f4-q8jf, the attacker can achieve RCE, potentially leading to full server compromise.

3. Affected Systems and Software Versions

Affected Versions:

• Elysia framework versions 1.4.0 through 1.4.16.

Fixed Version:

• The issue is resolved in version 1.4.17.

4. Recommended Mitigation Strategies

Immediate Mitigation:

• Upgrade: Upgrade to Elysia framework version 1.4.17 or later.
• Workaround: Remove the __proto__ key from the request body to prevent prototype pollution.

Long-term Mitigation:

• Code Review: Conduct a thorough code review to identify and fix similar vulnerabilities.
• Security Training: Educate developers on the risks of prototype pollution and best practices for secure coding.
• Regular Updates: Ensure that all dependencies and frameworks are regularly updated to the latest versions.

5. Impact on European Cybersecurity Landscape

Impact Analysis:

• Widespread Use: Elysia is a popular framework for request validation and client-server communication, making this vulnerability potentially widespread.
• Critical Infrastructure: Organizations using Elysia in critical infrastructure or sensitive applications are at high risk.
• Regulatory Compliance: Non-compliance with security standards can lead to regulatory penalties and loss of trust.

Regulatory and Compliance Implications:

• GDPR: Breaches resulting from this vulnerability can lead to data leaks, violating GDPR regulations.
• NIS Directive: Critical infrastructure providers must ensure robust security measures to comply with the NIS Directive.

6. Technical Details for Security Professionals

Vulnerability Details:

• Prototype Pollution: The mergeDeep function in Elysia allows the __proto__ property to be merged, leading to prototype pollution.
• Combination with GHSA-8vch-m3f4-q8jf: When combined with another vulnerability, this can escalate to RCE.

References:

• GitHub Advisories:
  • GHSA-8vch-m3f4-q8jf
  • GHSA-hxj9-33pp-j2cc
• GitHub Pull Request:
  • Pull Request #1564
• GitHub Commits:
  • Commit 26935bf76ebc43b4a43d48b173fc853de43bb51e
  • Commit 3af978663e437dccc6c1a2a3aff4b74e1574849e
• NVD Entry:
  • CVE-2025-66456

Additional Resources:

• Elysia GitHub Repository: Elysia
• Proof of Concept: Elysia PoC

Conclusion: This vulnerability highlights the importance of regular security audits and updates. Organizations should prioritize upgrading to the latest version of Elysia and implement robust security measures to mitigate the risk of prototype pollution and RCE.