Skip to main content
← All vulnerabilities
CVE-2026-77696

Timing Side-Channel in SM2 Signature Generation

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 4.0.3, 3.6.5, 3.5.9, 3.4.8, 3.0.23, and 1 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • OpenSSL OpenSSL

    From 4.0.0 · fixed in 4.0.3; From 3.6.0 · fixed in 3.6.5; From 3.5.0 · fixed in 3.5.9; From 3.4.0 · fixed in 3.4.8; From 3.0.0 · fixed in 3.0.23; From 1.1.1 · fixed in 1.1.1zj

References 5

openssl-library.org

GitHub · openssl/openssl