CVE-2026-27978

MEDIUM EPSS 10.0%
Published Mar 18, 20263mo ago · Modified Jun 17, 20262w ago
5.3 CVSS 4.0
Medium
Find Similar
Published Mar 18, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
5.3
Exploitability
—
Impact
—
Vector string
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction P
Scope X

Threat Intelligence

EPSS Exploit Probability
10.0% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-352 Cross-Site Request Forgery (CSRF) Authentication

Affected Products 1

VendorProductVersionRange
vercelnext.js*≥16.0.1  –  <16.1.7

References 3

  • github.com https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8
    Patch
  • github.com https://github.com/vercel/next.js/releases/tag/v16.1.7
    Release Notes
  • github.com https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcx
    MitigationVendor Advisory

Remediation

  • github.com https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8
    Patch