{"id":"CVE-2026-77696","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-77696","generatedAt":"2026-10-28T02:56:57.687Z","title":"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.","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.","published":"2026-09-29T16:17:11.000Z","lastModified":"2026-10-08T01:20:41.000Z","status":"Analyzed","sourceIdentifier":"openssl-security@openssl.org","cvss":{"version":"3.1","score":3.7,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"},"cwe":["CWE-208"],"affected":["openssl/openssl"],"epss":{"score":0.00396,"percentile":0.33587,"date":"2026-10-26","history":[{"date":"2026-09-30","score":0.00243,"percentile":0.14022}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.40%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-09-29T16:17:11.000Z","detail":{"score":"3.7","severity":"LOW","publishedAt":"2026-09-29T16:17:11.493Z"},"summary":"New CVE, low severity (CVSS 3.7)."}],"references":[{"url":"https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://openssl-library.org/news/secadv/20260929.txt","tags":["Vendor Advisory"],"source":"openssl-security@openssl.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-77696","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}