CVE-2024-48949: Indutny Elliptic Signature Vulnerability

CVE-2024-48949 Overview

CVE-2024-48949 is a critical cryptographic vulnerability in the Elliptic package for Node.js, a widely-used JavaScript implementation of elliptic curve cryptography. The vulnerability exists in the verify function within lib/elliptic/eddsa/index.js, which fails to properly validate EdDSA (Edwards-curve Digital Signature Algorithm) signatures. Specifically, the implementation omits critical validation checks for the signature's S component, allowing malformed or crafted signatures to pass verification when they should be rejected.

This improper verification of cryptographic signatures (CWE-347) enables attackers to potentially bypass signature-based authentication mechanisms, forge digital signatures, or compromise the integrity of cryptographically signed data in applications relying on the vulnerable library.

Critical Impact

Attackers can bypass EdDSA signature verification by submitting malformed signatures, potentially compromising authentication systems, data integrity, and cryptographic protocols in applications using the Elliptic library prior to version 6.5.6.

Affected Products

• Indutny Elliptic library versions prior to 6.5.6
• Node.js applications using vulnerable Elliptic package versions
• Systems and applications with Elliptic as a transitive dependency

Discovery Timeline

• 2024-10-10 - CVE-2024-48949 published to NVD
• 2025-11-25 - Last updated in NVD database

Technical Details for CVE-2024-48949

Vulnerability Analysis

The vulnerability stems from missing boundary validation in the EdDSA signature verification routine. In elliptic curve cryptography, a valid EdDSA signature consists of two components: R (a curve point) and S (a scalar value). The S component must satisfy specific mathematical constraints to be considered valid—it must be non-negative and less than the curve order (n).

The vulnerable implementation in lib/elliptic/eddsa/index.js omits the validation check sig.S().gte(sig.eddsa.curve.n) || sig.S().isNeg(), which would normally reject signatures where S is greater than or equal to the curve order, or where S is negative. Without this check, the verification function may accept mathematically invalid signatures that should be rejected according to the EdDSA specification.

This vulnerability was discovered using Wycheproof test vectors, a project designed to test cryptographic libraries against known edge cases and attack vectors.

Root Cause

The root cause is an incomplete implementation of the EdDSA signature verification algorithm. The missing validation allows signatures with out-of-range S values to be processed as valid. In properly implemented EdDSA verification, the S component must be checked to ensure it falls within the valid range [0, n) where n is the order of the curve's base point. The omission of this check creates a scenario where malformed signatures can pass verification, undermining the security guarantees of the cryptographic protocol.

Attack Vector

This vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can craft malicious EdDSA signatures with S values that exceed the curve order or are negative. When these signatures are submitted to an application using the vulnerable Elliptic library, the verification function may incorrectly return success.

The attack scenario involves:

1. Identifying an application that uses the Elliptic library for EdDSA signature verification
2. Crafting a signature with an invalid S component (either negative or exceeding the curve order)
3. Submitting the malformed signature to bypass verification checks
4. Potentially gaining unauthorized access, forging authenticated messages, or compromising data integrity

Since the Elliptic library is a foundational cryptographic component used by many Node.js applications and as a transitive dependency in numerous packages, the attack surface can be significant.

Detection Methods for CVE-2024-48949

Indicators of Compromise

• Unexpected signature verification successes in application logs for signatures that should fail validation
• EdDSA signatures with unusually large S component values in authentication or verification requests
• Anomalous authentication patterns where previously invalid signatures now succeed
• Log entries showing signature data with S values outside expected ranges

Detection Strategies

• Implement dependency scanning in CI/CD pipelines to detect vulnerable Elliptic package versions (prior to 6.5.6)
• Use Software Composition Analysis (SCA) tools to identify transitive dependencies on vulnerable Elliptic versions
• Monitor application logs for signature verification anomalies or unexpected authentication successes
• Deploy runtime application security testing to detect cryptographic validation bypasses

Monitoring Recommendations

• Enable verbose logging for signature verification operations in affected applications
• Implement alerting for authentication success rates that deviate from established baselines
• Monitor npm audit or yarn audit outputs for known vulnerabilities in the Elliptic package
• Track dependency versions across development and production environments using SBOM (Software Bill of Materials)

How to Mitigate CVE-2024-48949

Immediate Actions Required

• Update the Elliptic package to version 6.5.6 or later in all affected applications
• Run npm audit or yarn audit to identify vulnerable dependencies including transitive dependencies
• Review and update lock files (package-lock.json or yarn.lock) to ensure patched versions are installed
• Audit recent signature verification logs for potential exploitation attempts

Patch Information

The vulnerability has been addressed in Elliptic version 6.5.6. The fix adds the missing validation check to ensure the S component of EdDSA signatures is within the valid range. The patch can be reviewed in the GitHub commit and the version comparison shows all changes between the vulnerable and patched versions.

Organizations using products with Elliptic as a dependency should also consult vendor-specific advisories such as the NetApp Security Advisory for guidance on affected products and patches.

Workarounds

• If immediate patching is not possible, consider implementing additional signature validation at the application layer before passing to the Elliptic library
• Isolate applications using the vulnerable library from external network access where feasible
• Implement Web Application Firewall (WAF) rules to detect and block requests containing potentially malformed EdDSA signatures
• Consider temporarily switching to an alternative cryptographic library that properly validates EdDSA signatures

# Update Elliptic package to patched version
npm update elliptic@^6.5.6

# Or specify exact version in package.json and reinstall
npm install elliptic@6.5.6 --save

# Verify installed version
npm list elliptic

# Check for vulnerabilities in dependencies
npm audit