Threat Intelligence Database

A cryptographic weakness exists in sm-crypto versions prior to 0.5.0 where the default SM2 key pair generation in Node.js uses a weak pseudo-random number generator seeded from predictable sources. This flaw allows attackers who can observe Math.random() outputs and estimate key generation time to recover private keys and forge signatures. The issue is fixed in version 0.5.0.

The npm package sm-crypto version 0.4.0 and earlier generates SM2 private keys and signing ephemeral scalars using a predictable random number generator in Node.js environments. The library relies on jsbn's SecureRandom, which attempts to seed from window.crypto.getRandomValues in browsers but falls back to non-cryptographic sources (Math.random and wall clock time) in Node.js because window is undefined. This fallback results in keys and ephemeral values that are predictable by attackers who can observe some outputs of Math.random and estimate the generation time. This vulnerability affects the default key generation path without requiring special configuration.