CVE-2026-77696
Published: September 30, 2026Last modified: October 10, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 3.7 |
| Attack Vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | LOW |
| Integrity impact | NONE |
| Availability impact | NONE |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | openssl | Fixed (3.0.22-r1) |
| 25 LTS | openssl | Fixed (3.5.9-r0) | |
| Stream | openssl | Fixed (3.5.9-r0) | |
| Hardened Containers | 23 LTS | openssl | Fixed (3.0.22-r1) |
| 25 LTS | openssl | Fixed (3.5.9-r0) | |
| Stream | openssl | Fixed (3.5.9-r0) |
References
- 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