CVE-2026-73567 PUBLISHED

sm-crypto: Predictable SM2 key generation in Node.js: default RNG uses Math.random + wall clock

Assigner: GitHub_M
Reserved: 12.08.2026 Published: 13.08.2026 Updated: 13.08.2026

sm-crypto provides JavaScript implementations of the Chinese cryptographic algorithms SM2, SM3, and SM4. Prior to 0.5.0, the default no-argument sm2.generateKeyPairHex() path in Node.js uses the module-wide SecureRandom instance in src/sm2/utils.js, supplied by jsbn@1.1.0, which seeds an ARC4 stream from Math.random() and new Date().getTime() because window.crypto.getRandomValues is unavailable even though globalThis.crypto exists. An attacker who can observe the process's Math.random() outputs and estimate the key-generation time can reconstruct the seed, recover generated SM2 private keys, and predict signing ephemeral scalars used to forge signatures. This issue is fixed in version 0.5.0.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS Score: 9.1

Product Status

Vendor JuneAndGreen
Product sm-crypto
Versions
  • Version < 0.5.0 is affected

References

Problem Types

  • CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) CWE