CVE-2025-64767

Comprehensive Technical Analysis of CVE-2025-64767

1. Vulnerability Assessment and Severity Evaluation

CVE ID: CVE-2025-64767

Description: The vulnerability affects the hpke-js library, a Hybrid Public Key Encryption (HPKE) module built on top of the Web Cryptography API. Prior to version 1.7.5, a race condition in the public SenderContext Seal() API allows for the reuse of the same AEAD (Authenticated Encryption with Associated Data) nonce for multiple Seal() calls. This reuse can lead to a complete loss of confidentiality and integrity of the produced messages.

CVSS Score: 9.1

Severity Evaluation:

• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: None
• Exploitability: High
• Remediation Level: Official-Fix

The high CVSS score of 9.1 indicates a critical vulnerability that can be easily exploited, leading to severe impacts on confidentiality and integrity.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Network Interception: An attacker could intercept encrypted messages and exploit the nonce reuse to decrypt the messages, leading to a loss of confidentiality.
• Man-in-the-Middle (MitM) Attacks: An attacker could modify the encrypted messages without detection, leading to a loss of integrity.

Exploitation Methods:

• Nonce Reuse Detection: An attacker can detect nonce reuse by analyzing multiple encrypted messages and identifying patterns.
• Cryptographic Analysis: Once nonce reuse is detected, the attacker can use cryptographic techniques to decrypt the messages and potentially forge new messages.

3. Affected Systems and Software Versions

Affected Software:

• hpke-js versions prior to 1.7.5

Affected Systems:

• Any system or application that uses hpke-js for encryption and decryption operations.
• Web applications that rely on the Web Cryptography API for secure communications.

4. Recommended Mitigation Strategies

Immediate Actions:

• Upgrade to Version 1.7.5: Ensure that all instances of hpke-js are upgraded to version 1.7.5 or later, which includes the patch for this vulnerability.
• Monitor for Suspicious Activity: Implement monitoring to detect any unusual patterns in encrypted communications that may indicate nonce reuse.

Long-Term Strategies:

• Regular Security Audits: Conduct regular security audits of cryptographic libraries and modules.
• Code Reviews: Implement thorough code reviews, especially for critical security components.
• Automated Testing: Use automated testing tools to detect race conditions and other concurrency issues.

5. Impact on Cybersecurity Landscape

Immediate Impact:

• Data Breaches: Potential for significant data breaches due to the loss of confidentiality.
• Integrity Compromise: Compromised integrity can lead to unauthorized modifications of data.

Long-Term Impact:

• Trust Erosion: Loss of trust in cryptographic libraries and modules, affecting the broader cybersecurity ecosystem.
• Increased Scrutiny: Greater scrutiny on the implementation and security of cryptographic algorithms and libraries.

6. Technical Details for Security Professionals

Technical Overview:

• Race Condition: The vulnerability stems from a race condition in the SenderContext Seal() API, where multiple threads or asynchronous operations can reuse the same AEAD nonce.
• AEAD Nonce Reuse: In AEAD, nonce reuse can lead to catastrophic failure of the encryption scheme, allowing an attacker to decrypt messages and forge new ones.

Code Analysis:

• Vulnerable Code: The issue is located in the senderContext.ts file, specifically in the Seal() method.

  // Example of vulnerable code (simplified)
  class SenderContext {
    async Seal(message: Uint8Array): Promise<Uint8Array> {
      // Race condition occurs here
      const nonce = generateNonce();
      const encryptedMessage = await crypto.subtle.encrypt(
        { name: "AES-GCM", iv: nonce },
        this.key,
        message
      );
      return encryptedMessage;
    }
  }
  

Patch Details:

• Fix: The patch ensures that each Seal() call uses a unique nonce, preventing reuse.

  // Example of patched code (simplified)
  class SenderContext {
    async Seal(message: Uint8Array): Promise<Uint8Array> {
      const nonce = generateUniqueNonce(); // Ensure unique nonce generation
      const encryptedMessage = await crypto.subtle.encrypt(
        { name: "AES-GCM", iv: nonce },
        this.key,
        message
      );
      return encryptedMessage;
    }
  }
  

References:

• GitHub Commit
• GitHub Security Advisory

By addressing this vulnerability promptly and thoroughly, organizations can mitigate the risks associated with nonce reuse and ensure the security of their encrypted communications.