Next.js version 12.2.6 is a minor release following 12.2.5, primarily focusing on internal updates and dependency alignment. Developers upgrading from 12.2.5 will find a generally seamless transition, with no significant breaking changes expected. The core functionality and feature set remain consistent, ensuring existing Next.js applications continue to function as intended.
A notable difference lies in the updated @next/swc dependencies, the Rust-based compiler and bundler for Next.js. These @next/swc packages, tailored for various operating systems and architectures, have been bumped from 12.2.5 to 12.2.6, likely incorporating performance improvements and bug fixes within the compilation pipeline. Similarly, @next/env has been updated, suggesting tweaks to environment variable handling and configuration loading.
While the vast majority of dependencies across dependencies, devDependencies, and optionalDependencies remain at the same versions, some @next/polyfill packages and @next/react-refresh-utils got updated from 12.2.5 to 12.2.6. Also, a difference is that the new version has react-server-dom-webpack":"0.0.0-experimental-d2c9e834a-20220601" while the older version doesn't have it.
The release dates show a significant difference in time since its publishing date; this is relevant if your projects need the newest releases related to bug fixes or security. For development, version 12.2.6 builds upon the stability of 12.2.5, offering refinements under the hood. Developers seeking the latest optimizations and minor enhancements should update, while those content with 12.2.5 can remain without immediate concern.
All the vulnerabilities related to the version 12.2.6 of the package
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 missing cache-control header may lead to CDN caching empty reply
Next.js before 13.4.20-canary.13 lacks a cache-control header and thus empty prefetch responses may sometimes be cached by a CDN, causing a denial of service to all users requesting the same URL via that CDN. Cloudflare considers these requests cacheable assets.
Denial of Service condition in Next.js image optimization
The image optimization feature of Next.js contained a vulnerability which allowed for a potential Denial of Service (DoS) condition which could lead to excessive CPU consumption.
Not affected:
next.config.js file is configured with images.unoptimized set to true or images.loader set to a non-default value.This issue was fully patched in Next.js 14.2.7. We recommend that users upgrade to at least this version.
Ensure that the next.config.js file has either images.unoptimized, images.loader or images.loaderFile assigned.
Brandon Dahler (brandondahler), AWS Dimitrios Vlastaras
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 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.
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
PostCSS line return parsing error
An issue was discovered in PostCSS before 8.4.31. It affects linters using PostCSS to parse external Cascading Style Sheets (CSS). There may be \r discrepancies, as demonstrated by @font-face{ font:(\r/*);} in a rule.
This vulnerability affects linters using PostCSS to parse external untrusted CSS. An attacker can prepare CSS in such a way that it will contains parts parsed by PostCSS as a CSS comment. After processing by PostCSS, it will be included in the PostCSS output in CSS nodes (rules, properties) despite being originally included in a comment.