CVE-2026-77696
Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel.
Impact
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.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Openssl | Openssl | from 1.1.1 before 1.1.1zj from 3.0.0 before 3.0.23 from 3.4.0 before 3.4.8 from 3.5.0 before 3.5.9 from 3.6.0 before 3.6.5 from 4.0.0 before 4.0.3 |
Weakness classification
References
- NVD record
- CVE.org record
- https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9
- https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb
- https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64
- https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440
- https://openssl-library.org/news/secadv/20260929.txt