Next.js version 15.1.6 represents a minor update over the previous stable release, 15.1.5, primarily focusing on internal package version bumps and refinements. While the core functionality and React framework remain consistent, developers should note that @next/env, @next/swc and @next/font are updated in dependencies and devDependencies respectively, aligning them with the newer version number. Additionally, the release dates differ, indicating recent changes and improvements incorporated in the newer version.
A key area of change is in the optional dependencies, specifically the @next/swc-* packages, which are native binaries optimized for different platforms and architectures. Updating to 15.1.6 ensures developers are leveraging the latest SWC (Speedy Web Compiler) build, potentially leading to performance improvements, especially during local development and build processes. Furthermore, the releaseDate field indicates 15.1.6 has a more recent build date than 15.1.5.
While both versions share the same core set of dependencies and development dependencies like Webpack, Babel, and TypeScript, developers should update especially due to the recent release date, and the upgrades in SWC, which is the engine for compilation and optimization. For developers already using Next.js 15.x, upgrading to 15.1.6 is recommended to benefit from these incremental improvements and ensure compatibility with the latest ecosystem tools. These updates are intended to result in minor bug fixes, performance improvements, and refined internal functionality.
All the vulnerabilities related to the version 15.1.6 of the package
Next.JS vulnerability can lead to DoS via cache poisoning
A vulnerability affecting Next.js has been addressed. It impacted versions 15.0.4 through 15.1.8 and involved a cache poisoning bug leading to a Denial of Service (DoS) condition.
Under certain conditions, this issue may allow a HTTP 204 response to be cached for static pages, leading to the 204 response being served to all users attempting to access the page
More details: CVE-2025-49826
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.
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.
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