{"id":"CVE-2026-54872","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-54872","generatedAt":"2026-10-28T01:45:48.600Z","title":"Issue summary: The generic elliptic-curve scalar multiplication used for ECDSA and SM2 signature operations with curves that do not have a dedicated implementation leaks information about the secret nonce through timing.","description":"Issue summary: The generic elliptic-curve scalar multiplication used for\nECDSA and SM2 signature operations with curves that do not have a dedicated\nimplementation leaks information about the secret nonce through timing.\n\nImpact summary: An attacker able to measure 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: The generic elliptic-curve scalar multiplication used for\ncurves that do not have a dedicated constant-time implementation pads the\nsecret scalar with non-constant-time BIGNUM operations, so the time taken\ndepends on the value of the secret scalar derived from the ECDSA and SM2 nonce.\n\nThe leak is very small; observing it requires a large number of\nmeasurements. The effect is largest for curves whose group order lies\non a machine-word boundary, such as brainpoolP384r1.\n\nApplications using ECDSA signing over the Brainpool and other generic prime\ncurves, and SM2 signing on platforms that use the generic implementation,\nare vulnerable to this issue.\n\nThe NIST curves P-256, P-384 and P-521 use dedicated constant-time\nimplementations and are not affected.\n\nFIPS Impact: no\nThe FIPS modules are not affected: the approved NIST curves used in the FIPS\nprovider have dedicated constant-time implementations and do not use the\naffected code path.","published":"2026-09-29T16:17:09.000Z","lastModified":"2026-10-08T01:19:05.000Z","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":0.00428,"percentile":0.36755,"date":"2026-10-26","history":[{"date":"2026-09-30","score":0.00263,"percentile":0.16327}]},"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 (0.43%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"scored","label":"Newly scored","at":"2026-09-29T20:15:07.000Z","detail":{"from":null,"score":"3.7","severity":"LOW","fromSeverity":null},"summary":"Now scored CVSS 3.7 LOW."},{"kind":"new","label":"New CVE","at":"2026-09-29T16:17:09.000Z","detail":{"score":null,"severity":null,"publishedAt":"2026-09-29T16:17:08.623Z"},"summary":"New CVE, low severity (CVSS 3.7)."}],"references":[{"url":"https://github.com/openssl/openssl/commit/1a5bee8dc57430a2be69cd1ffe7fec6a62f4f179","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/3f7e1363dccec6f7732bb9e9fa471bb6e4aa68cb","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/7d83bc7764999dfd91b83b4f0815b45390422afd","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/8166827a78aad164a07aa86dea2b425403ced471","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-2026-54872","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."}