CVE-2026-77696Timing Side-Channel in SM2 Signature Generation
Updated under an hour ago ()
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It affects OpenSSL. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 3.7 LOW (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-208
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- openssl
- NVD analysis
- Analyzed
- Record last updated
- Sep 29, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
OpenSSL OpenSSL openssl:openssl (from the name) | from 4.0.0 before 4.0.3; from 3.6.0 before 3.6.5; from 3.5.0 before 3.5.9; from 3.4.0 before 3.4.8; from 3.0.0 before 3.0.23; from 1.1.1 before 1.1.1zj | CNA record |
openssl openssl 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 | NVD |
References
- https://openssl-library.org/news/secadv/20260929.txtvendor-advisory
- https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cbpatch
- https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9patch
- https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440patch
- https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.