{
  "canonical_id": "nextjs--CVE-2026-27978",
  "system_id": "nextjs",
  "display_name": "Next.js",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": "Next.js: null origin can bypass Server Actions CSRF checks",
  "summary": "## Summary\n`origin: null` was treated as a \"missing\" origin during Server Action CSRF validation. As a result, requests from opaque contexts (such as sandboxed iframes) could bypass origin verification instead of being validated as cross-origin requests.\n\n## Impact\nAn attacker could induce a victim browser to submit Server Actions from a sandboxed context, potentially executing state-changing actions with victim credentials (CSRF).\n\n## Patches\nFixed by treating `'null'` as an explicit origin value and enforcing host/origin checks unless `'null'` is explicitly allowlisted in `experimental.serverActions.allowedOrigins`.  \n\n## Workarounds\nIf upgrade is not immediately possible:\n- Add CSRF tokens for sensitive Server Actions.\n- Prefer `SameSite=Strict` on sensitive auth cookies.\n- Do not allow `'null'` in `serverActions.allowedOrigins` unless intentionally required and additionally protected.",
  "published_at": "2026-03-17T15:30:14Z",
  "updated_at": "2026-03-17T15:46:43.484729Z",
  "severity": "medium",
  "cvss_score": 4.0,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx",
  "secondary_source_urls": [
    "https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8",
    "https://github.com/vercel/next.js",
    "https://github.com/vercel/next.js/releases/tag/v16.1.7"
  ],
  "aliases": [
    "CVE-2026-27978",
    "GHSA-mq59-m269-xvcx"
  ],
  "cve_ids": [
    "CVE-2026-27978"
  ],
  "ghsa_ids": [
    "GHSA-mq59-m269-xvcx"
  ],
  "osv_ids": [
    "GHSA-mq59-m269-xvcx"
  ],
  "affected_versions": [
    "introduced=16.0.1, fixed<16.1.7"
  ],
  "fixed_versions": [
    "16.1.7"
  ],
  "package_name": "next",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/nextjs/cases/nextjs-cve-2026-27978.md",
  "secure_code_topics": [
    "authz-server-side-recheck",
    "proxy-trust-boundary",
    "token-cookie-storage"
  ],
  "status": "generated",
  "triage_reasons": [],
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
  "last_verified_at": null,
  "last_run_id": null,
  "evidence_bundle": null,
  "historical_status": null,
  "latest_status": null,
  "browser_evidence": {
    "required": false,
    "present": false,
    "refs": []
  },
  "repro_profile_id": "nextjs-proxy-boundary",
  "artifact_mode": "official-source",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Next.js"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 1
  }
}