Vercel Next Js

Next.js 9.5.015.5.12/16.1.6 Request Smuggling via Rewrite (DELETE/OPTIONS chunked)
CVE-2026-29057 - March 18, 2026

Next.js is a React framework for building full-stack web applications. Starting in version 9.5.0 and prior to versions 15.5.13 and 16.1.7, 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. 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. The vulnerability originated in an upstream library vendored by Next.js. It is fixed in Next.js 15.5.13 and 16.1.7 by updating that dependencys 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. If upgrading is not immediately possible, block chunked `DELETE`/`OPTIONS` requests on rewritten routes at the edge/proxy, and/or enforce authentication/authorization on backend routes.

HTTP Request Smuggling

Next.js 10.0.016.1.6: Unbounded Disk Cache Enables DoS via Image Optimization
CVE-2026-27980 - March 18, 2026

Next.js is a React framework for building full-stack web applications. Starting in version 10.0.0 and prior to version 16.1.7, the default Next.js image optimization disk cache (`/_next/image`) did not have a configurable upper bound, allowing unbounded cache growth. An attacker could generate many unique image-optimization variants and exhaust disk space, causing denial of service. This is fixed in version 16.1.7 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. If upgrading is not immediately possible, periodically clean `.next/cache/images` and/or reduce variant cardinality (e.g., tighten values for `images.localPatterns`, `images.remotePatterns`, and `images.qualities`).

Resource Exhaustion

Next.js <16.1.7 PPR Resume-Body Buffering DoS (next-resume header)
CVE-2026-27979 - March 18, 2026

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, a request containing the `next-resume: 1` header (corresponding with a PPR resume request) would buffer request bodies without consistently enforcing `maxPostponedStateSize` in certain setups. The previous mitigation protected minimal-mode deployments, but equivalent non-minimal deployments remained vulnerable to the same unbounded postponed resume-body buffering behavior. In applications using the App Router with Partial Prerendering capability enabled (via `experimental.ppr` or `cacheComponents`), an attacker could send oversized `next-resume` POST payloads that were buffered without consistent size enforcement in non-minimal deployments, causing excessive memory usage and potential denial of service. This is fixed in version 16.1.7 by enforcing size limits across all postponed-body buffering paths and erroring when limits are exceeded. If upgrading is not immediately possible, block requests containing the `next-resume` header, as this is never valid to be sent from an untrusted client.

Allocation of Resources Without Limits or Throttling

Next.js CSRF via 'origin:null' in Server Actions v16.0.116.1.6
CVE-2026-27978 - March 17, 2026

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, `origin: null` was treated as a "missing" origin during Server Action CSRF validation. As a result, requests from opaque contexts (such as sandboxed iframes) could bypass origin verification instead of being validated as cross-origin requests. An attacker could induce a victim browser to submit Server Actions from a sandboxed context, potentially executing state-changing actions with victim credentials (CSRF). This is fixed in version 16.1.7 by treating `'null'` as an explicit origin value and enforcing host/origin checks unless `'null'` is explicitly allowlisted in `experimental.serverActions.allowedOrigins`. If upgrading is not immediately possible, add CSRF tokens for sensitive Server Actions, prefer `SameSite=Strict` on sensitive auth cookies, and/or do not allow `'null'` in `serverActions.allowedOrigins` unless intentionally required and additionally protected.

Session Riding

Next.js 16.0.1-16.1.6 Dev Server Origin Null Bypass
CVE-2026-27977 - March 17, 2026

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in `next dev`, cross-site protection for internal websocket endpoints could treat `Origin: null` as a bypass case even if `allowedDevOrigins` is configured, allowing privacy-sensitive/opaque contexts (for example sandboxed documents) to connect unexpectedly. If a dev server is reachable from attacker-controlled content, an attacker may be able to connect to the HMR websocket channel and interact with dev websocket traffic. This affects development mode only. Apps without a configured `allowedDevOrigins` still allow connections from any origin. The issue is fixed in version 16.1.7 by validating `Origin: null` through the same cross-site origin-allowance checks used for other origins. If upgrading is not immediately possible, do not expose `next dev` to untrusted networks and/or block websocket upgrades to `/_next/webpack-hmr` when `Origin` is `null` at the proxy.

1385

Next.js 15.3.0–15.3.2 AppRouter Cache Poisoning via RSC
CVE-2025-49005 - July 03, 2025

Next.js is a React framework for building full-stack web applications. In Next.js App Router from 15.3.0 to before 15.3.3 and Vercel CLI from 41.4.1 to 42.2.0, a cache poisoning vulnerability was found. The issue allowed page requests for HTML content to return a React Server Component (RSC) payload instead under certain conditions. When deployed to Vercel, this would only impact the browser cache, and would not lead to the CDN being poisoned. When self-hosted and deployed externally, this could lead to cache poisoning if the CDN does not properly distinguish between RSC / HTML in the cache keys. This issue has been resolved in Next.js 15.3.3.

HTTP Request Smuggling

Next.js 15.0.4–15.1.7 Cache Poisoning DoS (HTTP 204) – Fixed 15.1.8
CVE-2025-49826 - July 03, 2025

Next.js is a React framework for building full-stack web applications. From versions 15.0.4-canary.51 to before 15.1.8, a cache poisoning bug leading to a Denial of Service (DoS) condition was found in Next.js. This issue does not impact customers hosted on Vercel. 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. This issue has been addressed in version 15.1.8.

HTTP Request Smuggling

Next.js Dev Server Source Exposure - v13.0–<14.2.30 & v15.0–<15.2.2
CVE-2025-48068 - May 30, 2025

Next.js is a React framework for building full-stack web applications. In versions starting from 13.0 to before 14.2.30 and 15.0.0 to before 15.2.2, Next.js 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. This issue has been patched in versions 14.2.30 and 15.2.2.

1385

Next.js 14.2.x/15.1.x Race-Condition: pageProps leakage via x-now-route-matches
CVE-2025-32421 - May 14, 2025

Next.js is a React framework for building full-stack web applications. Versions prior to 14.2.24 and 15.1.6 have a race-condition vulnerability. This issue only affects the Pages Router under certain misconfigurations, causing normal endpoints to serve `pageProps` data instead of standard HTML. This issue was patched in versions 15.1.6 and 14.2.24 by stripping the `x-now-route-matches` header from incoming requests. Applications hosted on Vercel's platform are not affected by this issue, as the platform does not cache responses based solely on `200 OK` status without explicit `cache-control` headers. Those who self-host Next.js deployments and are unable to upgrade immediately can mitigate this vulnerability by stripping the `x-now-route-matches` header from all incoming requests at the content development network and setting `cache-control: no-store` for all responses under risk. The maintainers of Next.js strongly recommend only caching responses with explicit cache-control headers.

Race Condition

Next.js Middleware SubreqID Header Leak (Fix 12.3.6,13.5.10,14.2.26,15.2.4)
CVE-2025-30218 - April 02, 2025

Next.js is a React framework for building full-stack web applications. To mitigate CVE-2025-29927, Next.js validated the x-middleware-subrequest-id which persisted across multiple incoming requests. However, this subrequest ID is sent to all requests, even if the destination is not the same host as the Next.js application. Initiating a fetch request to a third-party within Middleware will send the x-middleware-subrequest-id to that third party. This vulnerability is fixed in 12.3.6, 13.5.10, 14.2.26, and 15.2.4.

Information Disclosure

Authorization Bypass in Next.js Middleware (v1.11.4 & <12.3.5/13.5.9/14.2.25/15.2.3)
CVE-2025-29927 - March 21, 2025

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.

AuthZ

Next.js Server Action DoS before 13.5.8/14.2.21/15.1.2
CVE-2024-56332 - January 03, 2025

Next.js is a React framework for building full-stack web applications. Starting in version 13.0.0 and prior to versions 13.5.8, 14.2.21, and 15.1.2, Next.js is vulnerable to a Denial of Service (DoS) attack that allows attackers to construct requests that leaves requests to Server Actions hanging until the hosting provider cancels the function execution. This vulnerability can also be used as a Denial of Wallet (DoW) attack when deployed in providers billing by response times. (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. The issue was resolved in Next.js 13.5.8, 14.2.21, and 15.1.2. We recommend that users upgrade to a safe version. There are no official workarounds.

Allocation of Resources Without Limits or Throttling

Next.js Authorization Bypass Vulnerability in Middleware Pathname Handling
CVE-2024-51479 - December 17, 2024

Next.js is a React framework for building full-stack web applications. In affected versions if a Next.js application is performing authorization in middleware based on pathname, it was possible for this authorization to be bypassed for pages directly under the application's root directory. For example: * [Not affected] `https://example.com/` * [Affected] `https://example.com/foo` * [Not affected] `https://example.com/foo/bar`. This issue is 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.

AuthZ

DoS via Image Optimization in Next.js <14.2.7 (images.unoptimized)
CVE-2024-47831 7.5 - High - October 14, 2024

Next.js is a React Framework for the Web. Cersions on the 10.x, 11.x, 12.x, 13.x, and 14.x branches before version 14.2.7 contain a vulnerability in the image optimization feature which allows for a potential Denial of Service (DoS) condition which could lead to excessive CPU consumption. Neither the `next.config.js` file that is configured with `images.unoptimized` set to `true` or `images.loader` set to a non-default value nor the Next.js application that is hosted on Vercel are affected. This issue was fully patched in Next.js `14.2.7`. As a workaround, ensure that the `next.config.js` file has either `images.unoptimized`, `images.loader` or `images.loaderFile` assigned.

Stack Exhaustion

Next.js SSR cache poisoning via pages router (v13.5.1-14.2.9)
CVE-2024-46982 - September 17, 2024

Next.js is a React framework for building full-stack web applications. By sending a crafted HTTP request, it is possible to poison the cache of a non-dynamic server-side rendered route in the pages router (this does not affect the app router). When this crafted request is sent it could coerce Next.js to cache a route that is meant to not be cached and send a `Cache-Control: s-maxage=1, stale-while-revalidate` header which some upstream CDNs may cache as well. To be potentially affected all of the following must apply: 1. Next.js between 13.5.1 and 14.2.9, 2. Using pages router, & 3. Using non-dynamic server-side rendered routes e.g. `pages/dashboard.tsx` not `pages/blog/[slug].tsx`. This vulnerability was resolved in Next.js v13.5.7, v14.2.10, and later. We recommend upgrading regardless of whether you can reproduce the issue or not. There are no official or recommended workarounds for this issue, we recommend that users patch to a safe version.

Insecure Direct Object Reference / IDOR

DoS via Crash in Next.js before 13.5 (Vercel)
CVE-2024-39693 - July 10, 2024

Next.js is a React framework. A Denial of Service (DoS) condition was identified in Next.js. Exploitation of the bug can trigger a crash, affecting the availability of the server. his vulnerability was resolved in Next.js 13.5 and later.

Next.js SSRF in Server Actions (14.1.0) via Host header manipulation
CVE-2024-34351 - May 14, 2024

Next.js is a React framework that can provide building blocks to create web applications. A Server-Side Request Forgery (SSRF) vulnerability was identified in Next.js Server Actions. If the `Host` header is modified, and the below conditions are also met, an attacker may be able to make requests that appear to be originating from the Next.js application server itself. The required conditions are 1) Next.js is running in a self-hosted manner; 2) the Next.js application makes use of Server Actions; and 3) the Server Action performs a redirect to a relative path which starts with a `/`. This vulnerability was fixed in Next.js `14.1.1`.

Next.js <13.5.1 Response Queue Poisoning via HTTP Rewrites
CVE-2024-34350 - May 14, 2024

Next.js is a React framework that can provide building blocks to create web applications. Prior to 13.5.1, an inconsistent interpretation of a crafted HTTP request meant that requests are treated as both a single request, and two separate requests by Next.js, leading to desynchronized responses. This led to a response queue poisoning vulnerability in the affected Next.js versions. For a request to be exploitable, the affected route also had to be making use of the [rewrites](https://nextjs.org/docs/app/api-reference/next-config-js/rewrites) feature in Next.js. The vulnerability is resolved in Next.js `13.5.1` and newer.

DoS via CDN cache-control omission in Next.js prefetch (<=13.4.20-canary.13)
CVE-2023-46298 7.5 - High - October 22, 2023

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.

RCE in next.js 12.2.3 with Node.js >15 via strict unhandledRejection
CVE-2022-36046 5.3 - Medium - August 31, 2022

Next.js is a React framework that can provide building blocks to create web applications. All of the following must be true to be affected by this CVE: Next.js version 12.2.3, Node.js version above v15.0.0 being used with strict `unhandledRejection` exiting AND using next start or a [custom server](https://nextjs.org/docs/advanced-features/custom-server). Deployments on Vercel ([vercel.com](https://vercel.com/)) are not affected along with similar environments where `next-server` isn't being shared across requests.

Improper Check for Unusual or Exceptional Conditions

Next.js is a React framework
CVE-2022-23646 7.5 - High - February 17, 2022

Next.js is a React framework. Starting with version 10.0.0 and prior to version 12.1.0, Next.js is vulnerable to User Interface (UI) Misrepresentation of Critical Information. In order to be affected, the `next.config.js` file must have an `images.domains` array assigned and the image host assigned in `images.domains` must allow user-provided SVG. If the `next.config.js` file has `images.loader` assigned to something other than default, the instance is not affected. Version 12.1.0 contains a patch for this issue. As a workaround, change `next.config.js` to use a different `loader configuration` other than the default.

User Interface (UI) Misrepresentation of Critical Information

Next.js is a React framework
CVE-2022-21721 7.5 - High - January 28, 2022

Next.js is a React framework. Starting with version 12.0.0 and prior to version 12.0.9, vulnerable code could allow a bad actor to trigger a denial of service attack for anyone using i18n functionality. In order to be affected by this CVE, one must use next start or a custom server and the built-in i18n support. Deployments on Vercel, along with similar environments where invalid requests are filtered before reaching Next.js, are not affected. A patch has been released, `next@12.0.9`, that mitigates this issue. As a workaround, one may ensure `/${locale}/_next/` is blocked from reaching the Next.js instance until it becomes feasible to upgrade.

Next.js is a React framework
CVE-2021-43803 7.5 - High - December 10, 2021

Next.js is a React framework. In versions of Next.js prior to 12.0.5 or 11.1.3, invalid or malformed URLs could lead to a server crash. In order to be affected by this issue, the deployment must use Next.js versions above 11.1.0 and below 12.0.5, Node.js above 15.0.0, and next start or a custom server. Deployments on Vercel are not affected, along with similar environments where invalid requests are filtered before reaching Next.js. Versions 12.0.5 and 11.1.3 contain patches for this issue.

Next.js is a React framework
CVE-2021-39178 6.1 - Medium - August 31, 2021

Next.js is a React framework. Versions of Next.js between 10.0.0 and 11.0.0 contain a cross-site scripting vulnerability. In order for an instance to be affected by the vulnerability, the `next.config.js` file must have `images.domains` array assigned and the image host assigned in `images.domains` must allow user-provided SVG. If the `next.config.js` file has `images.loader` assigned to something other than default or the instance is deployed on Vercel, the instance is not affected by the vulnerability. The vulnerability is patched in Next.js version 11.1.1.

XSS

Next.js is an open source website development framework to be used with the React library
CVE-2021-37699 6.1 - Medium - August 12, 2021

Next.js is an open source website development framework to be used with the React library. In affected versions specially encoded paths could be used when pages/_error.js was statically generated allowing an open redirect to occur to an external site. In general, this redirect does not directly harm users although can allow for phishing attacks by redirecting to an attacker's domain from a trusted domain. We recommend everyone to upgrade regardless of whether you can reproduce the issue or not. The issue has been patched in release 11.1.0.

Open Redirect

Next.js versions >=9.5.0 and <9.5.4 are vulnerable to an Open Redirect
CVE-2020-15242 6.1 - Medium - October 08, 2020

Next.js versions >=9.5.0 and <9.5.4 are vulnerable to an Open Redirect. Specially encoded paths could be used with the trailing slash redirect to allow an open redirect to occur to an external site. In general, this redirect does not directly harm users although can allow for phishing attacks by redirecting to an attackers domain from a trusted domain. The issue is fixed in version 9.5.4.

Open Redirect