GHSA-P9J2-GV94-2WF4

Vulnerability from github – Published: 2026-07-22 23:02 – Updated: 2026-07-22 23:02
VLAI
Summary
Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname
Details

Impact

A rewrites() or redirects() rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname, regardless of the rule's hostname suffix. For a rewrite, Next.js proxies the request to that arbitrary host and serves the response from the application's origin, leading to Server-Side Request forgery. A redirects() rule configured this way is vulnerable to an Open Redirect.

This affects any destination that puts a dynamic segment in the hostname, whether from the path:

// next.config.js
module.exports = {
  async rewrites() {
    return [
      {
        source: '/:tenant',
        destination: 'https://:tenant.api.example.com',
      },
    ]
  },
}

or from a has capture:

// next.config.js
module.exports = {
  async rewrites() {
    return [
      {
        source: '/',
        has: [{ type: 'query', key: 'region', value: '(?<region>.+)' }],
        destination: 'https://:region.api.example.com',
      },
    ]
  },
}

Workarounds

If you cannot upgrade immediately, do not build the hostname of an external rewrites() or redirects() destination from user-controlled input. If a dynamic subdomain is required, constrain the value to hostname-safe characters: value: '(?<region>[a-z0-9-]+)'.

Severity
8.3 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "next"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "12.0.0"
            },
            {
              "fixed": "15.5.21"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "next"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "16.0.0"
            },
            {
              "fixed": "16.2.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-64645"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-22T23:02:23Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Impact\n\nA `rewrites()` or `redirects()` rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname, regardless of the rule\u0027s\u00a0hostname suffix. For a rewrite, Next.js proxies the request to that arbitrary host and serves the response from the application\u0027s origin, leading to Server-Side Request forgery. A `redirects()` rule configured this way is vulnerable to an Open Redirect.\n\nThis affects any destination that puts a dynamic segment in the hostname, whether from the path:\n\n```javascript\n// next.config.js\nmodule.exports = {\n  async rewrites() {\n    return [\n      {\n        source: \u0027/:tenant\u0027,\n        destination: \u0027https://:tenant.api.example.com\u0027,\n      },\n    ]\n  },\n}\n```\n\nor from a `has` capture:\n\n```javascript\n// next.config.js\nmodule.exports = {\n  async rewrites() {\n    return [\n      {\n        source: \u0027/\u0027,\n        has: [{ type: \u0027query\u0027, key: \u0027region\u0027, value: \u0027(?\u003cregion\u003e.+)\u0027 }],\n        destination: \u0027https://:region.api.example.com\u0027,\n      },\n    ]\n  },\n}\n```\n\n## Workarounds\n\nIf you cannot upgrade immediately, do not build the hostname of an external `rewrites()` or `redirects()` destination from user-controlled input. If a dynamic subdomain is required, constrain the value to hostname-safe characters:  `value: \u0027(?\u003cregion\u003e[a-z0-9-]+)\u0027`.",
  "id": "GHSA-p9j2-gv94-2wf4",
  "modified": "2026-07-22T23:02:23Z",
  "published": "2026-07-22T23:02:23Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/security/advisories/GHSA-p9j2-gv94-2wf4"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/commit/35f501357e9b0fe7c950b0d6aa8fcf5343f707e9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/commit/d3033266c6dff23f7be71e19341fe3a8c6e2c599"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vercel/next.js"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v15.5.21"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v16.2.11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname"
}



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