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Vulnerability record · CVE-2026-77696 · published 29 September 2026

CVE-2026-77696: Openssl vulnerability

OOpenssl · Openssl

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.

3.7 CVSS 3.1 Low EPSS 0.45% · top 60.0% CWE-208 · CWE-208
3.7CVSS 3.1 base score
0.45%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
10 Nov 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9 Patch
https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb Patch
https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64 Patch
https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440 Patch
https://openssl-library.org/news/secadv/20260929.txt Vendor Advisory
https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-77696), CISA KEV, FIRST EPSS (scores of 2026-11-13). This page is refreshed as NVD updates the record.