GHSA-4992-7RV2-5PVQ

Vulnerability from github – Published: 2026-03-13 20:41 – Updated: 2026-03-13 20:41
VLAI
Summary
Undici has CRLF Injection in undici via `upgrade` option
Details

Impact

When an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to:

  1. Inject arbitrary HTTP headers
  2. Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)

The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters:

// lib/dispatcher/client-h1.js:1121
if (upgrade) {
  header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n`
}

Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

Workarounds

Sanitize the upgrade option string before passing to undici:

function sanitizeUpgrade(value) {
  if (/[\r\n]/.test(value)) {
    throw new Error('Invalid upgrade value')
  }
  return value
}

client.request({
  upgrade: sanitizeUpgrade(userInput)
})
Severity
4.6 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.24.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "undici"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.24.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-1527"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-93"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-13T20:41:26Z",
    "nvd_published_at": "2026-03-12T21:16:25Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nWhen an application passes user-controlled input to the `upgrade` option of `client.request()`, an attacker can inject CRLF sequences (`\\r\\n`) to:\n\n1. Inject arbitrary HTTP headers\n2. Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)\n\nThe vulnerability exists because undici writes the `upgrade` value directly to the socket without validating for invalid header characters:\n\n```javascript\n// lib/dispatcher/client-h1.js:1121\nif (upgrade) {\n  header += `connection: upgrade\\r\\nupgrade: ${upgrade}\\r\\n`\n}\n```\n\n### Patches\n\n Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.\n\n### Workarounds\n\nSanitize the `upgrade` option string before passing to undici:\n\n```javascript\nfunction sanitizeUpgrade(value) {\n  if (/[\\r\\n]/.test(value)) {\n    throw new Error(\u0027Invalid upgrade value\u0027)\n  }\n  return value\n}\n\nclient.request({\n  upgrade: sanitizeUpgrade(userInput)\n})\n```",
  "id": "GHSA-4992-7rv2-5pvq",
  "modified": "2026-03-13T20:41:26Z",
  "published": "2026-03-13T20:41:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nodejs/undici/security/advisories/GHSA-4992-7rv2-5pvq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1527"
    },
    {
      "type": "WEB",
      "url": "https://hackerone.com/reports/3487198"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nodejs/undici"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Undici has CRLF Injection in undici via `upgrade` option"
}



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