---
cve: "CVE-2026-27978"
severity: "MEDIUM"
cvss: 5.3
epss: "20%"
vendor: "vercel"
kev: false
exploited: false
published: "2026-03-18 00:16:20"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-15T07:39:46+02:00"
---

# CVE-2026-27978

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |

## Patch verfügbar (OSV)

- bdf3e3577a6d55ea186a48238d61fbd8da07a626 (Commit)
- a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8 (Commit)

## Referenzen

- <https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx>
- <https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8>
- <https://github.com/vercel/next.js/releases/tag/v16.1.7>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-27978) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_