CVE-2024-42459: Elliptic EDDSA Signature Malleability Flaw

CVE-2024-42459 Overview

CVE-2024-42459 is a cryptographic vulnerability affecting the Elliptic package version 6.5.6 for Node.js. The vulnerability stems from EDDSA signature malleability due to a missing signature length check, which allows zero-valued bytes to be removed or appended to signatures. This improper verification of cryptographic signatures (CWE-347) can undermine the integrity guarantees that digital signatures are designed to provide.

Critical Impact

Signature malleability vulnerabilities can allow attackers to modify signatures in ways that still pass verification, potentially enabling transaction replay attacks, authentication bypasses, or other security issues in systems relying on the uniqueness of signatures.

Affected Products

• Indutny Elliptic 6.5.6 for Node.js
• Applications and services using the affected Elliptic package version
• Cryptocurrency wallets and blockchain applications utilizing EDDSA signatures through this library

Discovery Timeline

• 2024-08-02 - CVE-2024-42459 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-42459

Vulnerability Analysis

The Elliptic package is a widely-used JavaScript library that implements various elliptic curve cryptography operations, including the Edwards-curve Digital Signature Algorithm (EDDSA). The vulnerability exists because the library fails to perform proper length validation on EDDSA signatures during the verification process.

EDDSA signatures should have a fixed, canonical length. When the signature verification routine does not enforce this length constraint, it creates a malleability condition. An attacker can take a valid signature and modify it by either removing trailing zero-valued bytes or appending additional zero-valued bytes, producing a different signature that still validates against the same message and public key.

This vulnerability is classified under CWE-347 (Improper Verification of Cryptographic Signature), as the verification logic does not properly validate all aspects of the signature format.

Root Cause

The root cause of this vulnerability is the absence of a signature length check in the EDDSA verification implementation. The Elliptic library's signature parsing logic accepts signatures of varying lengths rather than enforcing the expected canonical format. When zero bytes at the end of a signature are treated as optional or when additional zero bytes can be appended without invalidating the signature, the cryptographic guarantee of signature uniqueness is compromised.

Attack Vector

The attack vector for this vulnerability is network-based and does not require authentication. An attacker with access to a valid EDDSA signature can manipulate it by:

1. Removing trailing zero-valued bytes from the signature
2. Appending zero-valued bytes to create an alternative valid signature
3. Using these modified signatures in systems that rely on signature uniqueness for deduplication or replay protection

The modified signature will still pass verification against the original message and public key, potentially bypassing security controls that assume each valid signature is unique. This is particularly concerning for blockchain and cryptocurrency applications where transaction signatures must be canonical to prevent double-spending or replay attacks.

Detection Methods for CVE-2024-42459

Indicators of Compromise

• Multiple valid signatures appearing for the same transaction or message with different byte lengths
• Signature verification logs showing signatures with unexpected trailing bytes
• Unusual patterns in signature lengths deviating from the expected EDDSA signature format

Detection Strategies

• Audit application dependencies to identify usage of elliptic package version 6.5.6
• Use software composition analysis (SCA) tools to scan for vulnerable package versions in your Node.js projects
• Monitor signature verification operations for signatures with non-canonical lengths
• Review transaction logs for potential signature duplication or modification patterns

Monitoring Recommendations

• Implement logging for all cryptographic signature operations including signature lengths
• Set up alerts for dependency vulnerabilities using tools like npm audit or Snyk
• Monitor application behavior for anomalies in signature processing
• Track package versions across your development and production environments

How to Mitigate CVE-2024-42459

Immediate Actions Required

• Update the Elliptic package to a patched version that includes the signature length validation fix
• Review applications using EDDSA signatures through the Elliptic library for potential impact
• Audit transaction and signature logs for evidence of exploitation
• Consider implementing application-level signature length validation as an additional defense layer

Patch Information

The vulnerability has been addressed through a pull request that adds proper signature length validation to the EDDSA implementation. The fix ensures that signatures must conform to the expected canonical length, rejecting any signatures with additional or missing bytes. For detailed patch information, refer to GitHub Pull Request #317. Additional vendor guidance is available in the NetApp Security Advisory.

Workarounds

• Implement application-level validation to check EDDSA signature lengths before passing them to the verification function
• Add signature canonicalization logic to normalize signatures before verification
• Consider using alternative cryptographic libraries with proper signature format enforcement until the patch is applied
• For critical applications, implement additional signature uniqueness checks at the application layer

# Check for vulnerable package version in your Node.js project
npm list elliptic

# Update to a patched version
npm update elliptic

# Run security audit to identify vulnerable dependencies
npm audit