Vulnerabilities in pkg:npm/hono

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-v8w9-8mx6-g223",
  "modified" : "2026-10-02T22:36:06Z",
  "published" : "2026-03-11T00:31:47Z",
  "aliases" : [ "CVE-2026-56763" ],
  "summary" : "Hono vulnerable to Prototype Pollution possible through __proto__ key allowed in parseBody({ dot: true })",
  "details" : "## Summary\n\nWhen using `parseBody({ dot: true })` in HonoRequest, specially crafted form field names such as `__proto__.x` could create objects containing a `__proto__` property.\n\nIf the parsed result is later merged into regular JavaScript objects using unsafe merge patterns, this may lead to prototype pollution in the target object.\n\n## Details\n\nThe `parseBody({ dot: true })` feature supports dot notation to construct nested objects from form field names.\n\nIn previous versions, the `__proto__` path segment was not filtered. As a result, specially crafted keys such as `__proto__.x` could produce objects containing `__proto__` properties.\n\nWhile this behavior does not directly modify `Object.prototype` within Hono itself, it may become exploitable if the parsed result is later merged into regular JavaScript objects using unsafe merge patterns.\n\n## Impact\n\nApplications that merge parsed form data into regular objects using unsafe patterns (for example recursive deep merge utilities) may become vulnerable to prototype pollution.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "hono"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.12.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/security/advisories/GHSA-v8w9-8mx6-g223"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-56763"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/commit/ef902257e0beacbb83d2a9549b3b83e03514a6fe"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/honojs/hono"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/hono-prototype-pollution-via-proto-key-in-parsebody-with-dot-option"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-11T00:31:47Z",
    "nvd_published_at" : null
  }
}