Description
Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel.
Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key.
CWE: CWE-208: Observable Timing Discrepancy
Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel.
Applications performing SM2 signature generation are affected on all platforms.
FIPS Impact: no SM2 is not a FIPS algorithm.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:NWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| OpenSSL | OpenSSL | >= 4.0.0, < 4.0.3; >= 3.6.0, < 3.6.5; >= 3.5.0, < 3.5.9; >= 3.4.0, < 3.4.8; >= 3.0.0, < 3.0.23; >= 1.1.1, < 1.1.1zj |
References
- https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9Patch
- https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cbPatch
- https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64Patch
- https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440Patch
- https://openssl-library.org/news/secadv/20260929.txtVendor Advisory
Timeline
- Published
- Sep 29, 2026
- Last modified
- Nov 10, 2026
- NVD status
- Modified