{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "cc9159b5c60a8eb16bbac4525005e2b5880d3624"
            }
          ],
          "repo": "https://github.com/elysiajs/elysia",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-8hq9-phh3-p2wp"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-1321"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31865.json"
  },
  "details": "Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible.",
  "id": "CVE-2026-31865",
  "modified": "2026-04-01T23:10:29.352544297Z",
  "published": "2026-03-18T02:50:55.403Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31865.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/elysiajs/elysia/security/advisories/GHSA-8hq9-phh3-p2wp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31865"
    },
    {
      "type": "FIX",
      "url": "https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Elysia Cookie Value Prototype Pollution"
}