X25519 x86_64 assembly final reduction leaves non-canonical field element

{
  "id": "beec8c10f71b6e035aa0e7d0f44bd0255ceacf6a7486ac2f3b46e52004c49528",
  "url": "https://osv.dev/vulnerability/CVE-2026-10512",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "X25519 x86_64 assembly final reduction leaves non-canonical field element",
    "summary": "The X25519 x86_64 assembly implementation fails to clear the most significant bit during the final modular reduction, so the computed result may not be fully reduced modulo the field prime 2^255 - 19. This can leave the field element in a non-canonical form, producing an incorrect result from the scalar multiplication and potentially a wrong shared secret. The final carry-propagation chains in the x64 and AVX2 reduction routines could overflow into the top bit, and the high limb was not masked afterward, so the 255-bit field element was left non-canonical.",
    "evidence": "osv:CVE-2026-10512",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-10512",
      "aliases": [
        "CVE-2026-10512"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/wolfssl/wolfssl",
              "type": "GIT",
              "events": [
                {
                  "introduced": "37884f864d6fd9b04f44677cb04da15d0c9d6526"
                },
                {
                  "fixed": "ac01707f552c611fbd135cc723b2682b3e7f80f2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "5.6.4"
                      },
                      {
                        "last_affected": "5.9.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "cpe": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.6.4"
                      },
                      {
                        "fixed": "5.9.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.9.1-stable",
            "v5.9.0-stable",
            "v5.8.4-stable",
            "wolfEntropy2d",
            "v5.8.2-stable",
            "wolfEntropy1",
            "v5.8.0-stable",
            "v5.7.6-stable",
            "v5.7.4-stable",
            "v5.2.1",
            "v5.7.2-stable",
            "v5.7.0-stable",
            "v5.6.6-stable",
            "v5.6.4-stable"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-10512.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.907789197Z",
      "provider": "osv",
      "references": [
        "https://www.wolfssl.com/docs/security-vulnerabilities/",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10512.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-10512",
        "https://github.com/wolfSSL/wolfssl/pull/10536",
        "https://github.com/wolfSSL/wolfssl"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-682"
        ],
        "cna_assigner": "wolfSSL",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10512.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-10512",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 510883,
  "published_at": "2026-06-25T19:58:16.013+00:00"
}