{"id":"CVE-2026-77696","published":"2026-09-29T16:17:11.493","lastModified":"2026-09-29T21:27:41.130","description":"Issue summary: SM2 signature generation uses non-constant-time arithmetic\non secret values, forming a timing side-channel.\n\nImpact summary: An attacker able to measure SM2 signing times may learn\ninformation about the per-signature secret nonce, which over many signatures\ncan, via a lattice / Hidden Number Problem attack, lead to recovery of the\nprivate key.\n\nCWE: CWE-208: Observable Timing Discrepancy\n\nDescription: SM2 signature generation computes the signature value using\nvariable-time BIGNUM operations on the secret nonce and the private key, so\nthe time taken to produce an SM2 signature depends on these secret values,\nforming a timing side-channel.\n\nApplications performing SM2 signature generation are affected on all\nplatforms.\n\nFIPS Impact: no\nSM2 is not a FIPS algorithm.","cvssScore":3.7,"cvssSeverity":"LOW","cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","cwes":["CWE-208"],"vendors":[],"products":[],"references":[{"url":"https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9","tags":[]},{"url":"https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb","tags":[]},{"url":"https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64","tags":[]},{"url":"https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440","tags":[]},{"url":"https://openssl-library.org/news/secadv/20260929.txt","tags":[]}],"exploitRefs":[{"url":"https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9","tags":[]},{"url":"https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb","tags":[]},{"url":"https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64","tags":[]},{"url":"https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440","tags":[]}],"hasPoc":true,"ai":null}