# CVE-2026-27978: Next.js: null origin can bypass Server Actions CSRF checks

> CVE-2026-27978: Next.js: null origin can bypass Server Actions CSRF checks. CVSS 4.3 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-27978
Last updated: 2026-06-17T10:28:00Z

- Published: 2026-03-17 23:59 UTC · Updated: 2026-06-17 10:28 UTC · Assigner: GitHub\_M
- CVSS: 4.3 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- EPSS: 0.21%, 11th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-352

## Description

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.

## Affected vendors and products

- vercel: next.js

## Tracked companies

- [Vercel](https://rewindex.com/company/vercel.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-27978)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-27978)
- [https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8](https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8)
- [https://github.com/vercel/next.js/releases/tag/v16.1.7](https://github.com/vercel/next.js/releases/tag/v16.1.7)
- [https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx](https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx)

---

_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


---
Canonical: https://rewindex.com/cve/CVE-2026-27978 · Markdown: https://rewindex.com/cve/CVE-2026-27978.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-27978 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:16:34.694Z