CVE-2026-27978

Summary

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 Software

VendorProductVersion RangeStatus
vercelnext.js>= 16.0.1, < 16.1.7affected

Weaknesses

  • CWE-352: CWE-352: Cross-Site Request Forgery (CSRF)

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References