CVE-2025-14505: Elliptic ECDSA Signature Vulnerability

CVE-2025-14505 Overview

A cryptographic vulnerability has been identified in the ECDSA implementation of the Elliptic JavaScript package. The flaw generates incorrect signatures when an interim value of 'k' (computed per step 3.2 of RFC 6979) contains leading zeros. This occurs because the byte-length of 'k' is incorrectly computed, resulting in truncation during signature generation. The vulnerability breaks legitimate transactions and communications, and under certain conditions, attackers who obtain both a faulty signature from a vulnerable version and a correct signature for the same inputs could derive the secret key through cryptanalysis.

Critical Impact

Secret key exposure through cryptanalysis of faulty ECDSA signatures, potentially compromising cryptographic authentication and integrity across applications using the Elliptic package.

Affected Products

• Elliptic npm package versions ≤ 6.6.1
• All known versions of the Elliptic package at the time of disclosure
• Applications and services utilizing the Elliptic library for ECDSA signature operations

Discovery Timeline

• 2026-01-08 - CVE-2025-14505 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-14505

Vulnerability Analysis

This vulnerability stems from an implementation error in the ECDSA signature generation process within the Elliptic package. According to RFC 6979, deterministic ECDSA requires proper computation of the nonce value 'k' to ensure signature security. When 'k' values contain leading zero bytes, the Elliptic library incorrectly calculates the byte-length, causing the value to be truncated.

The truncation of 'k' results in mathematically incorrect signatures that may still appear valid in certain contexts but expose critical information about the private key. This is classified under CWE-1240 (Use of a Cryptographic Primitive with a Risky Implementation), as the core cryptographic algorithm is sound but the implementation introduces a fatal flaw.

The attack requires network access but involves high complexity, as the attacker must obtain both a faulty signature generated by the vulnerable implementation and a correct signature for identical inputs. This dual-signature requirement limits opportunistic exploitation but creates significant risk in environments where signature pairs may be observable.

Root Cause

The root cause lies in the incorrect byte-length calculation of the interim value 'k' during ECDSA signature generation. When 'k' has leading zeros, the library's length computation fails to account for these bytes properly, leading to truncation. This violates the mathematical requirements of RFC 6979 Section 3.2, where the full bit-length of 'k' must be preserved for secure signature generation.

The Elliptic package processes the deterministic nonce generation but introduces a subtle byte-handling error that manifests only when specific 'k' values with leading zeros are generated. This edge case in the number representation causes the signature to be computed with an incorrect nonce, fundamentally breaking the security guarantees of ECDSA.

Attack Vector

The attack vector is network-based, requiring the attacker to collect cryptographic signatures from the vulnerable system. The exploitation scenario involves:

1. Signature Collection: The attacker monitors or intercepts ECDSA signatures generated by the vulnerable Elliptic implementation
2. Fault Detection: Identifying signatures generated when 'k' contained leading zeros (resulting in faulty signatures)
3. Comparative Analysis: Obtaining a correct signature for the same message-key pair from a patched version or alternative implementation
4. Cryptanalysis: Using the mathematical relationship between the faulty and correct signatures to derive the secret key

The vulnerability mechanism relates to the ECDSA equation where the signature component s = k^(-1) * (z + r*d) mod n. When 'k' is incorrectly truncated, the resulting signature leaks information about the relationship between 'k' and the secret key 'd'. With access to both faulty and correct signatures, attackers can solve for the private key.

For technical details, refer to the GitHub Issue #321 Discussion and the HeroDevs vulnerability advisory.

Detection Methods for CVE-2025-14505

Indicators of Compromise

• Signature verification failures for legitimate transactions or communications that previously succeeded
• Inconsistent ECDSA signatures for identical inputs across different time periods
• Reports of authentication or integrity check failures in systems using Elliptic for cryptographic operations
• Unexpected signature lengths or malformed cryptographic outputs in application logs

Detection Strategies

• Audit npm dependencies for Elliptic package versions ≤ 6.6.1 using npm audit or similar dependency scanning tools
• Implement signature verification testing with known test vectors that include edge cases with leading zeros in 'k'
• Monitor cryptographic operation logs for signature generation anomalies or verification failures
• Deploy software composition analysis (SCA) tools to identify vulnerable Elliptic versions across the codebase

Monitoring Recommendations

• Enable detailed logging for all ECDSA signature operations in production environments
• Set up alerts for signature verification failures that may indicate exploitation attempts or faulty signatures
• Monitor network traffic for patterns consistent with signature collection attacks
• Implement runtime integrity checks for cryptographic operations using the Elliptic library

How to Mitigate CVE-2025-14505

Immediate Actions Required

• Inventory all applications and services using the Elliptic npm package
• Assess exposure by identifying systems performing ECDSA signature generation with affected versions
• Consider rotating cryptographic keys for systems that may have generated faulty signatures with vulnerable versions
• Evaluate the potential for key compromise in high-security environments where signature pairs may have been exposed

Patch Information

At the time of CVE publication, all known versions of the Elliptic package (≤ 6.6.1) are affected. Organizations should monitor the official GitHub repository for patch releases addressing this vulnerability. Once a patched version is available, update immediately using:

npm update elliptic

After patching, regenerate and re-sign any cryptographic material that may have been compromised. Consider key rotation as a precautionary measure for sensitive systems.

Workarounds

• Implement additional signature validation layers that verify signature correctness before transmission
• Consider using alternative ECDSA implementations temporarily while awaiting a patch
• Add application-level checks to detect and reject signatures that may be malformed due to 'k' truncation
• Isolate systems using Elliptic from networks where signature collection attacks are feasible

# Check for vulnerable Elliptic versions in your project
npm list elliptic
npm audit --audit-level=moderate

# Monitor for package updates
npm outdated elliptic