CVE-2026-27978
mediumpriority · track · 27EPSS 0.002 · 14 %ileexploit · PoCDEEURUUSEPSS · scored 2026-10-22
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2.1–5.3
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
exploits (1)
Public proof-of-concept and weaponised exploit code.
affected products (7)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-0748Vercel Next.js: Mehrere SchwachstellenDeutsch2026-03-16csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Vercel Next.js ausnutzen, um einen Denial of Service Angriff durchzuführen oder Sicherheitsmaßnahmen zu umgehen.
- GHSA-mq59-m269-xvcxNext.js: null origin can bypass Server Actions CSRF checks2026-03-17ghsa · osvUS
## Summary `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. ## Impact An attacker could induce a victim browser to submit Server Actions from a sandboxed context, potentially executing state-changing actions with victim credentials (CSRF). ## Patches Fixed by treating `'null'` as an explicit origin value and enforcing host/origin checks unless `'null'` is explicitly allowlisted in `experimental.serverActions.allowedOrigins`. ## Workarounds If upgrade is not immediately possible: - Add CSRF tokens for sensitive Server Actions. - Prefer `SameSite=Strict` on sensitive auth cookies. - Do not allow `'null'` in `serverActions.allowedOrigins` unless intentionally required and additionally protected.
also known as (5)
Other names and identifiers for this entity.
sources
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references (11)
External citations — patches, advisories, analysis.
- https://access.redhat.com/security/cve/cve-2026-27978cnnvd
- https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8cnnvd
- https://github.com/vercel/next.js/releasesPatchcnnvd
- https://github.com/vercel/next.js/releases/tag/v16.1.7cnnvd
- https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcxcnnvd
- https://github.com/vercel/next.js/commit/a27a11d78e748a8c7ccfd14b7759ad2b9bf097d8enisa_euvd
- https://github.com/vercel/next.js/releases/tag/v16.1.7enisa_euvd
- https://github.com/vercel/next.js/security/advisories/GHSA-mq59-m269-xvcxenisa_euvd
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