{
  "canonical_id": "nextjs--CVE-2026-29057",
  "system_id": "nextjs",
  "display_name": "Next.js",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": "Next.js: HTTP request smuggling in rewrites",
  "summary": "## 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).",
  "published_at": "2026-03-17T16:17:15Z",
  "updated_at": "2026-03-17T16:31:26.646070Z",
  "severity": "medium",
  "cvss_score": 4.0,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/vercel/next.js/security/advisories/GHSA-ggv3-7p47-pfv8",
  "secondary_source_urls": [
    "https://github.com/vercel/next.js/commit/dc98c04f376c6a1df76ec3e0a2d07edf4abdabd6",
    "https://github.com/vercel/next.js",
    "https://github.com/vercel/next.js/releases/tag/v15.5.13",
    "https://github.com/vercel/next.js/releases/tag/v16.1.7"
  ],
  "aliases": [
    "CVE-2026-29057",
    "GHSA-ggv3-7p47-pfv8"
  ],
  "cve_ids": [
    "CVE-2026-29057"
  ],
  "ghsa_ids": [
    "GHSA-ggv3-7p47-pfv8"
  ],
  "osv_ids": [
    "GHSA-ggv3-7p47-pfv8"
  ],
  "affected_versions": [
    "introduced=16.0.0-beta.0, fixed<16.1.7",
    "introduced=9.5.0, fixed<15.5.13"
  ],
  "fixed_versions": [
    "16.1.7",
    "15.5.13"
  ],
  "package_name": "next",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/nextjs/cases/nextjs-cve-2026-29057.md",
  "secure_code_topics": [
    "authz-server-side-recheck",
    "proxy-trust-boundary",
    "token-cookie-storage",
    "request-smuggling-boundary",
    "dependency-upgrade-policy"
  ],
  "status": "generated",
  "triage_reasons": [],
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
  "last_verified_at": null,
  "last_run_id": null,
  "evidence_bundle": null,
  "browser_evidence": {
    "required": false,
    "present": false,
    "refs": []
  },
  "repro_profile_id": "request-smuggling-generic",
  "artifact_mode": "official-source",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Next.js"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 1
  }
}