{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2026.05.1"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9000ecb52677da7d9676a61b729bab57dba99674"
            },
            {
              "fixed": "e66c5640664a31668926a24c0c84b6b6570dc0d9"
            }
          ],
          "repo": "https://github.com/sbabic/swupdate",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-295"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/109xxx/CVE-2026-109399.json"
  },
  "details": "SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.",
  "id": "CVE-2026-109399",
  "modified": "2026-10-14T02:30:18.664825893Z",
  "published": "2026-10-12T15:16:44.440Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/109xxx/CVE-2026-109399.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109399"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates"
    },
    {
      "type": "FIX",
      "url": "https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sbabic/swupdate"
    },
    {
      "type": "ARTICLE",
      "url": "https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c"
    },
    {
      "type": "ARTICLE",
      "url": "https://groups.google.com/g/swupdate/c/dsoMcGFnEns"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates"
}