{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.6.0"
              },
              {
                "last_affected": "0.7.6"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "13472f2f025498828b0823705c863602bdb08b70"
            },
            {
              "last_affected": "512a354dbd31e1895647df852d1565f9d408ed91"
            }
          ],
          "repo": "https://github.com/boazsegev/facil.io",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-125"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66729.json"
  },
  "details": "facil.io 0.6.0 through 0.7.6 contains an integer underflow vulnerability in the multipart MIME body parser that allows unauthenticated remote attackers to crash the server process by sending a crafted Content-Disposition header with an empty field name. Attackers can trigger a uint32_t wraparound in http_mime_parser.h causing an out-of-bounds memory read past the name pointer, resulting in a bus fault that crashes the handling worker with a single POST request.",
  "id": "CVE-2026-66729",
  "modified": "2026-07-28T03:56:05.229043302Z",
  "published": "2026-07-27T16:52:34.776Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66729.json"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/boazsegev/facil.io"
    },
    {
      "type": "EVIDENCE",
      "url": "https://github.com/theopaid/Out-of-Bounds-Read-in-facil.io-MIME-Parser-leads-to-Server-Crash"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-66729"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/facil-io-integer-underflow-dos-via-multipart-mime-body-parser"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "facil.io 0.6.0 - 0.7.6 Integer Underflow DoS via Multipart MIME Body Parser"
}