CVE-2026-77696 (GCVE-0-2026-77696)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:32 – Updated: 2026-09-29 16:51
VLAI
Title
Timing Side-Channel in SM2 Signature Generation
Summary
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
3.7 (Low)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-29 16:51 UTC
CWE
  • CWE-208 - Observable Timing Discrepancy
Assigner
References
Impacted products
Vendor Product Version CPE status
OpenSSL OpenSSL Affected: 4.0.0 , < 4.0.3 (semver)
Affected: 3.6.0 , < 3.6.5 (semver)
Affected: 3.5.0 , < 3.5.9 (semver)
Affected: 3.4.0 , < 3.4.8 (semver)
Affected: 3.0.0 , < 3.0.23 (semver)
Affected: 1.1.1 , < 1.1.1zj (custom)
guessed Create a notification for this product.
Date Public
2026-09-29 14:21
Credits
Vladimir Tokarev Igor Ustinov Viktor Dukhovni
Show details on NVD website
To clipboard 

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