Next.js CVE-2025-29927
CRITICALVulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization verification
MITRE ATT&CK
1 technique across 1 tactic: Defense Evasion The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS 9.1, EPSS 93.0%, PoC available, patch available. Next.js powers millions of production applications including major SaaS platforms. Any application relying on middleware for auth checks is directly vulnerable. The exploit is a single HTTP header addition. |
| Exploit ScenarioDerived | A SaaS application uses Next.js middleware to check session tokens and redirect unauthenticated users. An attacker adds x-middleware-subrequest: middleware to their HTTP request, causing Next.js to skip the middleware entirely. The attacker directly accesses admin dashboards, API routes, and protected resources without any authentication. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Mar 28, 2026
Next.js versions 1.11.4 through 15.2.2 contain a critical middleware authorization bypass via the x-middleware-subrequest header. Attackers can send crafted requests that skip middleware entirely, bypassing authentication, authorization, and security headers enforced at the middleware layer.
Earlier versions of this analysis (1)
Critical authorization bypass in Next.js allows attackers to skip middleware-based security controls using a crafted HTTP header.
RemediationAI
Update to Next.js 12.3.5, 13.5.9, 14.2.25, or 15.2.3. If patching is not feasible, configure your reverse proxy or CDN to strip the x-middleware-subrequest header from all incoming requests. Do not rely solely on middleware for critical authorization checks.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in npm
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Next.js middleware runs before route handlers and is commonly used for authentication, authorization, geo-restrictions, and CSP headers. The vulnerability exploits the x-middleware-subrequest internal header: when present with specific values, the framework treats the request as an internal subrequest and skips middleware execution entirely. This header is not stripped from external requests.
Know when Next.js gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3, it is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware. If patching to a safe version is infeasible, it is recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application. This vulnerability is fixed in 12.3.5, 13.5.9, 14.2.25, and 15.2.3.
Blast Radius
ecosystem impact- 16 npm packages depend on next (15 direct, 1 indirect)
Ecosystem-wide dependent count for version 13.0.0.
Executive ViewAI
Organizations using version 1.11.4 and face critical risk from CVE-2025-29927 rated CVSS 9.1. Successful exploitation could critically impact the confidentiality, integrity, and availability of affected systems. With an EPSS score of 93%, this vulnerability faces very high likelihood of exploitation. A patch is available and should be applied immediately given the critical severity.
Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Exploit-DB
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
Affected Products (CPE)GitHub Advisory
ZEIT Next.js before 2.4.1 has directory traversal under the /_next and /static request namespace, allowing attackers to
Improper restriction of excessive authentication attempts (CWE-307) in the 9Router AI router package (decolua/9router) b
Authorization bypass in the Sentry Next.js SDK affects @sentry/nextjs from 9.36.0 before 9.47.2, 10.x before 10.75.2, an
A remote code execution vulnerability (CVSS 9.1). Critical severity with potential for significant impact on affected sy
Authentication/authorization bypass in Clerk's official JavaScript SDKs (@clerk/nextjs, @clerk/nuxt, @clerk/astro, and t
Server-side request forgery in the Progress Sitefinity Next.js SDK npm package (@progress/sitefinity-nextjs-sdk, version
Prototype pollution in tRPC's @trpc/server package, specifically within the `formDataToObject` function used by the expe
A security vulnerability in Next.js applications. In Auth0 Next.js SDK (CVSS 7.7). High severity vulnerability requiring
Unauthenticated remote attackers can repeatedly invoke the revalidateProducts Server Action in the MarcosCamara01 Ecomme
Unauthenticated remote attackers can call the cleanCache handler in NotionNext's pages/api/cache.js to force cache inval
Concurrent token requests handled by the Auth0 Next.js SDK can be resolved through an internal in-flight request cache t
Next.js is a React framework for building full-stack web applications. Rated low severity (CVSS 3.7), this vulnerability