Next.js 14.2.12 represents a minor but potentially impactful update over version 14.2.11. While the core dependencies and peer dependencies remain largely consistent, developers should note the slight differences in the @next/swc versions for different platforms within the optionalDependencies. As both the packages contains the same dependencies and same size with less than 400kb difference between each other, the most important differences are: @next/polyfill-module, @next/react-refresh-utils and @next/env packages which was updated to support the core version.
This suggests targeted improvements or bug fixes within the SWC compiler specific to those platform architectures, possibly addressing performance or compatibility issues. The updated @next/polyfill-module, @next/react-refresh-utils and @next/env dependencies showcase a commitment to keeping the framework up to date and support the core version.
Developers who rely heavily on SWC for their build process or are targeting specific deployment environments like Darwin (macOS) or Linux should pay close attention to these changes. While the file count is constant the unpacked size reduced by 330kb, this could suggest refactoring to remove unused code or optimize code. As a patch version, 14.2.12 is unlikely to introduce major breaking changes, it's still recommended to review the changelog and test your application thoroughly after upgrading. The release represents a continuation of the framework's evolution, focusing on stability, performance, and compatibility.
All the vulnerabilities related to the version 14.2.12 of the package
Next.js authorization bypass vulnerability
If a Next.js application is performing authorization in middleware based on pathname, it was possible for this authorization to be bypassed.
This issue was patched in Next.js 14.2.15 and later.
If your Next.js application is hosted on Vercel, this vulnerability has been automatically mitigated, regardless of Next.js version.
There are no official workarounds for this vulnerability.
We'd like to thank tyage (GMO CyberSecurity by IERAE) for responsible disclosure of this issue.
Next.js Allows a Denial of Service (DoS) with Server Actions
A Denial of Service (DoS) attack allows attackers to construct requests that leaves requests to Server Actions hanging until the hosting provider cancels the function execution.
Note: Next.js server is idle during that time and only keeps the connection open. CPU and memory footprint are low during that time.
Deployments without any protection against long running Server Action invocations are especially vulnerable. Hosting providers like Vercel or Netlify set a default maximum duration on function execution to reduce the risk of excessive billing.
This is the same issue as if the incoming HTTP request has an invalid Content-Length header or never closes. If the host has no other mitigations to those then this vulnerability is novel.
This vulnerability affects only Next.js deployments using Server Actions.
This vulnerability was resolved in Next.js 14.2.21, 15.1.2, and 13.5.8. We recommend that users upgrade to a safe version.
There are no official workarounds for this vulnerability.
Thanks to the PackDraw team for responsibly disclosing this vulnerability.
Next.js Race Condition to Cache Poisoning
Summary
We received a responsible disclosure from Allam Rachid (zhero) for a low-severity race-condition vulnerability in Next.js. This issue only affects the Pages Router under certain misconfigurations, causing normal endpoints to serve pageProps data instead of standard HTML.
Credit
Thank you to Allam Rachid (zhero) for the responsible disclosure. This research was rewarded as part of our bug bounty program.
Authorization Bypass in Next.js Middleware
It is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware.
15.2.314.2.2513.5.912.3.5Note: Next.js deployments hosted on Vercel are automatically protected against this vulnerability.
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.
Information exposure in Next.js dev server due to lack of origin verification
A low-severity vulnerability in Next.js has been fixed in version 15.2.2. This issue may have allowed limited source code exposure when the dev server was running with the App Router enabled. The vulnerability only affects local development environments and requires the user to visit a malicious webpage while npm run dev is active.
Because the mitigation is potentially a breaking change for some development setups, to opt-in to the fix, you must configure allowedDevOrigins in your next config after upgrading to a patched version. Learn more.
Learn more: https://vercel.com/changelog/cve-2025-48068
Thanks to sapphi-red and Radman Siddiki for responsibly disclosing this issue.
Next.js Affected by Cache Key Confusion for Image Optimization API Routes
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. When images returned from API routes vary based on request headers (such as Cookie or Authorization), these responses could be incorrectly cached and served to unauthorized users due to a cache key confusion bug.
All users are encouraged to upgrade if they use API routes to serve images that depend on request headers and have image optimization enabled.
More details at Vercel Changelog
Next.js Content Injection Vulnerability for Image Optimization
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. The issue allowed attacker-controlled external image sources to trigger file downloads with arbitrary content and filenames under specific configurations. This behavior could be abused for phishing or malicious file delivery.
All users relying on images.domains or images.remotePatterns are encouraged to upgrade and verify that external image sources are strictly validated.
More details at Vercel Changelog
Next.js Improper Middleware Redirect Handling Leads to SSRF
A vulnerability in Next.js Middleware has been fixed in v14.2.32 and v15.4.7. The issue occurred when request headers were directly passed into NextResponse.next(). In self-hosted applications, this could allow Server-Side Request Forgery (SSRF) if certain sensitive headers from the incoming request were reflected back into the response.
All users implementing custom middleware logic in self-hosted environments are strongly encouraged to upgrade and verify correct usage of the next() function.
More details at Vercel Changelog