Vulnerability in OpenSSL
CVE-2026-77696
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- openssl-library.org/news/secadv/20260929.txt (vendor-advisory)
- github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb (patch)
- github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9 (patch)
- github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440 (patch)
- github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64 (patch)
Frequently asked questions
- What is CVE-2026-77696?
- CVE-2026-77696 is a low-severity vulnerability in OpenSSL, classified under CWE-208. CVSS score: 3.7/10. Published 2026-09-29.
- How severe is CVE-2026-77696?
- Low severity. CVSS v3 base score is 3.7 out of 10.