Package Instance

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](https://vercel.com/changelog/cve-2025-57822)

Next.js: HTTP request smuggling in rewrites
## Summary
When Next.js rewrites proxy traffic to an external backend, a crafted `DELETE`/`OPTIONS` request using `Transfer-Encoding: chunked` could trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes.

## Impact
An attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel. 

## Patches
The vulnerability originated in an upstream library vendored by Next.js. It is fixed by updating that dependency’s behavior so `content-length: 0` is added only when both `content-length` and `transfer-encoding` are absent, and `transfer-encoding` is no longer removed in that code path.

## Workarounds
If upgrade is not immediately possible:
- Block chunked `DELETE`/`OPTIONS` requests on rewritten routes at your edge/proxy.
- Enforce authentication/authorization on backend routes per our [security guidance](https://nextjs.org/docs/app/guides/data-security).

Denial of Service condition in Next.js image optimization
### Impact
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:**
- The `next.config.js` file is configured with `images.unoptimized` set to `true` or `images.loader` set to a non-default value.
- The Next.js application is hosted on Vercel. 

### Patches
This issue was fully patched in Next.js `14.2.7`. We recommend that users upgrade to at least this version.

### Workarounds
Ensure that the `next.config.js` file has either `images.unoptimized`, `images.loader` or `images.loaderFile` assigned.

#### Credits
Brandon Dahler (brandondahler), AWS
Dimitrios Vlastaras

Improper Input Validation
Next handling invalid or malformed URLs could lead to a server crash. Deployments on Vercel are not affected, along with similar environments where invalid requests are filtered before reaching Next.js.

Next.js: Unbounded next/image disk cache growth can exhaust storage
## Summary
The default Next.js image optimization disk cache (`/_next/image`) did not have a configurable upper bound, allowing unbounded cache growth.

## Impact
An attacker could generate many unique image-optimization variants and exhaust disk space, causing denial of service. Note that this does not impact platforms that have their own image optimization capabilities, such as Vercel.

## Patches
Fixed by adding an LRU-backed disk cache with `images.maximumDiskCacheSize`, including eviction of least-recently-used entries when the limit is exceeded. Setting `maximumDiskCacheSize: 0` disables disk caching. 

## Workarounds
If upgrade is not immediately possible:
- Periodically clean `.next/cache/images`.
- Reduce variant cardinality (e.g., tighten values for `images.localPatterns`, `images.remotePatterns`, and `images.qualities`)

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](https://vercel.com/changelog/cve-2025-57752)

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.

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](https://vercel.com/changelog/cve-2025-55173)

Next.js authorization bypass vulnerability
### Impact
If a Next.js application is performing authorization in middleware based on pathname, it was possible for this authorization to be bypassed.

### Patches
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.

### Workarounds
There are no official workarounds for this vulnerability.

#### Credits
We'd like to thank [tyage](http://github.com/tyage) (GMO CyberSecurity by IERAE) for responsible disclosure of this issue.