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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-73567: 0.44% estimated exploitation activity in the next 30 days; percentile 38.63 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary sm-crypto (npm package 0.4.0, the latest release, published 2026-01-20) generates SM2 private keys and signing ephemeral scalars from a single module-wide RNG instance (src/sm2/utils.js: const rng = new SecureRandom()). SecureRandom is jsbn's PRNG, which seeds an ARC4 stream from window.crypto.getRandomValues when available. In Node.js — sm-crypto's primary runtime — window is undefined, so the CSPRNG branch is skipped and the seed pool is instead filled from Math.random() (V8 xorshift128+, recoverable from a few outputs) plus new Date().getTime() (wall clock, attacker-estimable). Node does expose Web Crypto as globalThis.crypto, but jsbn checks window.crypto, not globalThis.crypto, so the secure path is never taken. Consequently every SM2 private key produced by the default sm2.generateKeyPairHex() and every signing ephemeral scalar is derived from non-cryptographic sources and is predictable by an attacker who can observe a few Math.random() outputs and estimate the…

Published by the source

24 Jul 2026, 21:50 UTC

Last modified by the source

13 Aug 2026, 17:55 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-vh45-f885-3848

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-vh45-f885-3848

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-vh45-f885-3848

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# Patch Next advisory brief: CVE-2026-73567

Advisory: sm-crypto: Predictable SM2 key generation in Node.js: default RNG uses Math.random + wall clock
IDs: CVE-2026-73567, GHSA-vh45-f885-3848
Record: https://patchnext.com/advisories/cve-2026-73567 (revision 3, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: sm-crypto 0.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm sm-crypto: affected < 0.5.0; fixed in 0.5.0

## Suggested inspection (read-only)
- `npm ls sm-crypto --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on sm-crypto.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-vh45-f885-3848 (GitHub-reviewed advisory GHSA-vh45-f885-3848 lists affected ranges: npm sm-crypto >=0 <0.5.0)
- Verified: https://osv.dev/vulnerability/GHSA-vh45-f885-3848 (OSV record GHSA-vh45-f885-3848 lists affected ranges: npm sm-crypto >=0 <0.5.0 (fixed))

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