GHSA-GGV3-7P47-PFV8

Vulnerability from github – Published: 2026-03-17 16:17 – Updated: 2026-03-18 21:53
VLAI?
Summary
Next.js: HTTP request smuggling in rewrites
Details

Summary

When Next.js rewrites proxy traffic to an external backend, a crafted DELETE/OPTIONS request using Transfer-Encoding: chunked could trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes.

Impact

An attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel.

Patches

The vulnerability originated in an upstream library vendored by Next.js. It is fixed by updating that dependency’s behavior so content-length: 0 is added only when both content-length and transfer-encoding are absent, and transfer-encoding is no longer removed in that code path.

Workarounds

If upgrade is not immediately possible: - Block chunked DELETE/OPTIONS requests on rewritten routes at your edge/proxy. - Enforce authentication/authorization on backend routes per our security guidance.

Severity ?
6.3 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "next"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "16.0.0-beta.0"
            },
            {
              "fixed": "16.1.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "next"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "9.5.0"
            },
            {
              "fixed": "15.5.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-29057"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-444"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-17T16:17:15Z",
    "nvd_published_at": "2026-03-18T01:16:05Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\nWhen Next.js rewrites proxy traffic to an external backend, a crafted `DELETE`/`OPTIONS` request using `Transfer-Encoding: chunked` could trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes.\n\n## Impact\nAn attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel. \n\n## Patches\nThe vulnerability originated in an upstream library vendored by Next.js. It is fixed by updating that dependency\u2019s behavior so `content-length: 0` is added only when both `content-length` and `transfer-encoding` are absent, and `transfer-encoding` is no longer removed in that code path.\n\n## Workarounds\nIf upgrade is not immediately possible:\n- Block chunked `DELETE`/`OPTIONS` requests on rewritten routes at your edge/proxy.\n- Enforce authentication/authorization on backend routes per our [security guidance](https://nextjs.org/docs/app/guides/data-security).",
  "id": "GHSA-ggv3-7p47-pfv8",
  "modified": "2026-03-18T21:53:28Z",
  "published": "2026-03-17T16:17:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/security/advisories/GHSA-ggv3-7p47-pfv8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-29057"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/commit/dc98c04f376c6a1df76ec3e0a2d07edf4abdabd6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vercel/next.js"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v15.5.13"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v16.1.7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Next.js: HTTP request smuggling in rewrites"
}


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