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CVE-2026-77696 Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing…

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.

Affected products and versions

Product Affected versions Fixed in
OpenSSL 4.0 4.0.0 → < 4.0.3 4.0.3
OpenSSL 3.6 3.6.0 → < 3.6.5 3.6.5
OpenSSL 3.5 3.5.0 → < 3.5.9 3.5.9
OpenSSL 3.4 3.4.0 → < 3.4.8 3.4.8
OpenSSL 3.0 3.0.0 → < 3.0.23 3.0.23
OpenSSL 1.1 earliest → < 1.1.1zj 1.1.1zj

References

Timeline

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