Riskcovery

CVE-2026-77696

Timing Side-Channel in SM2 Signature Generation

State
Published
Severity
3.7 Low
Published
Sep 29, 2026
Updated
Sep 29, 2026
Reserved
Aug 21, 2026

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
3.13.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:NCISA-ADP

Weaknesses

  • CWE-208 Observable Timing Discrepancy

Affected Products

ProductVersions
OpenSSLOpenSSL
  • 4.0.0 to before 4.0.3Affected
  • 3.6.0 to before 3.6.5Affected
  • 3.5.0 to before 3.5.9Affected
  • 3.4.0 to before 3.4.8Affected
  • 3.0.0 to before 3.0.23Affected
  • 1.1.1 to before 1.1.1zjAffected

References

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