{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e08402bfad8db05b0df820daf4f08c9c65ab1f7b"
            },
            {
              "fixed": "bdf3e3577a6d55ea186a48238d61fbd8da07a626"
            }
          ],
          "repo": "https://github.com/vercel/next.js",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-mq59-m269-xvcx"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-352"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27978.json"
  },
  "details": "Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, `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. An attacker could induce a victim browser to submit Server Actions from a sandboxed context, potentially executing state-changing actions with victim credentials (CSRF). This is fixed in version 16.1.7 by treating `'null'` as an explicit origin value and enforcing host/origin checks unless `'null'` is explicitly allowlisted in `experimental.serverActions.allowedOrigins`. If upgrading is not immediately possible, add CSRF tokens for sensitive Server Actions, prefer `SameSite=Strict` on sensitive auth cookies, and/or do not allow `'null'` in `serverActions.allowedOrigins` unless intentionally required and additionally protected.",
  "id": "CVE-2026-27978",
  "modified": "2026-04-01T23:09:12.234424602Z",
  "published": "2026-03-17T23:59:22.600Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v16.1.7"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27978.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27978"
    },
    {
      "type": "FIX",
      "url": "https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Next.js: null origin can bypass Server Actions CSRF checks"
}