GHSA-8HQ9-PHH3-P2WP

Vulnerability from github – Published: 2026-03-17 16:17 – Updated: 2026-03-19 19:01
VLAI?
Summary
Elysia Cookie Value Prototype Pollution
Details

Impact

Elysia cookie can be overridden by prototype pollution , eg. __proto__

Sending cookie with the follows name can override cookie value:

__proto__=%7B%22injected%22%3A%22polluted%22%7D

Patches

Patched by 1.4.27

Workarounds

  1. Use t.Cookie validation to enforce validation value
  2. Prevent iterable over cookie if possible
Severity ?
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "elysia"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.4.27"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31865"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-17T16:17:41Z",
    "nvd_published_at": "2026-03-18T04:17:19Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nElysia cookie can be overridden by prototype pollution , eg. `__proto__`\n\nSending cookie with the follows name can override cookie value:\n```bash\n__proto__=%7B%22injected%22%3A%22polluted%22%7D\n```\n\n### Patches\nPatched by 1.4.27\n\n### Workarounds\n1. Use t.Cookie validation to enforce validation value\n2. Prevent iterable over cookie if possible",
  "id": "GHSA-8hq9-phh3-p2wp",
  "modified": "2026-03-19T19:01:12Z",
  "published": "2026-03-17T16:17:41Z",
  "references": [
    {
      "type": "WEB",
      "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": "WEB",
      "url": "https://github.com/elysiajs/elysia/commit/e9d6b1743fa7368ef942dce181f6a089757f6aab"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/elysiajs/elysia"
    }
  ],
  "schema_version": "1.4.0",
  "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"
}


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