EUVD-2025-7243

Comprehensive Technical Analysis of EUVD-2025-7243

1. Vulnerability Assessment and Severity Evaluation

Vulnerability Description: The vulnerability in Next.js, a popular React framework for building full-stack web applications, allows for the bypass of authorization checks when these checks are implemented in middleware. This issue affects specific versions of Next.js, ranging from version 1.11.4 up to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3.

Severity Evaluation: The vulnerability has a CVSS base score of 9.1, which is considered critical. The CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N indicates the following:

• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): None (N)
• User Interaction (UI): None (N)
• Scope (S): Unchanged (U)
• Confidentiality Impact (C): High (H)
• Integrity Impact (I): High (H)
• Availability Impact (A): None (N)

This high severity score underscores the critical nature of the vulnerability, which can lead to significant confidentiality and integrity impacts.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Network-Based Attacks: Given the CVSS vector, the vulnerability can be exploited over the network without requiring any special privileges or user interaction.
• Middleware Bypass: An attacker can craft HTTP requests with the x-middleware-subrequest header to bypass authorization checks implemented in middleware.

Exploitation Methods:

• Header Manipulation: By manipulating the x-middleware-subrequest header in HTTP requests, an attacker can trick the application into bypassing authorization checks.
• Automated Scripts: Attackers can use automated scripts to send malicious requests, potentially leading to unauthorized access to sensitive data or functionalities.

3. Affected Systems and Software Versions

Affected Versions:

• Next.js versions starting from 1.11.4 up to but not including 12.3.5, 13.5.9, 14.2.25, and 15.2.3.

Specific Version Ranges:

• 11.1.4 to < 12.3.5

• 15.0.0 to < 15.2.3

• 11.1.4 to ≤ 13.5.6
• 13.0.0 to < 13.5.9

• 14.0.0 to < 14.2.25

• 14.0.0 to < 14.2.25
• 15.0.0 to < 15.2.3

4. Recommended Mitigation Strategies

Immediate Mitigation:

• Patching: Upgrade to the patched versions of Next.js: 12.3.5, 13.5.9, 14.2.25, or 15.2.3.
• Header Filtering: If patching is not feasible, implement a filter to block external user requests containing the x-middleware-subrequest header.

Long-Term Mitigation:

• Code Review: Conduct a thorough code review to ensure that authorization checks are not solely reliant on middleware.
• Regular Updates: Maintain a regular update schedule for all dependencies and frameworks to mitigate future vulnerabilities.

5. Impact on European Cybersecurity Landscape

Regulatory Compliance:

• GDPR: Unauthorized access to personal data due to this vulnerability could result in GDPR violations, leading to significant fines and legal consequences.
• NIS Directive: Organizations in critical sectors must ensure robust cybersecurity measures, and this vulnerability could compromise their compliance status.

Economic Impact:

• Data Breaches: Potential data breaches could lead to financial losses, reputational damage, and loss of customer trust.
• Operational Disruption: Unauthorized access could disrupt business operations, leading to downtime and reduced productivity.

6. Technical Details for Security Professionals

Vulnerability Details:

• CVE ID: CVE-2025-29927
• GHSA ID: GHSA-f82v-jwr5-mffw
• References:
  • GitHub Security Advisory
  • NVD Entry
  • GitHub Commits
  • GitHub Commits
  • Next.js Releases
  • Next.js Releases

Mitigation Steps:

1. Identify Affected Systems: Use dependency management tools to identify systems running vulnerable versions of Next.js.
2. Update Dependencies: Upgrade to the patched versions of Next.js.
3. Implement Header Filtering: Configure web servers or application gateways to block requests with the x-middleware-subrequest header.
4. Monitor and Log: Implement monitoring and logging to detect and respond to any suspicious activities related to this vulnerability.

Conclusion: The vulnerability in Next.js poses a significant risk to organizations using the affected versions. Immediate patching and implementation of mitigation strategies are crucial to prevent unauthorized access and potential data breaches. Organizations must also ensure compliance with relevant regulations and maintain robust cybersecurity practices to safeguard against such vulnerabilities.