CVE-2026-44572
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedNext.js is a React framework for building full-stack web applications. From 12.2.0 to before 15.5.16 and 16.2.5, an external client could send a x-nextjs-data header on a normal request to a path handled by middleware that returns a redirect. When that happened, the middleware/proxy could treat the request as a data request and replace the standard Location redirect header with the internal x-nextjs-redirect header. Browsers do not follow x-nextjs-redirect, so the response became an unusable redirect for normal clients. If the application was deployed behind a CDN or reverse proxy that caches 3xx responses without varying on this header, a single attacker request could poison the cached redirect response for the affected path. Subsequent visitors could then receive a cached redirect response without a Location header, causing a denial of service for that redirect path until the cache entry expired or was purged. This vulnerability is fixed in 15.5.16 and 16.2.5.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceNext.js versions 12.2.0 through 15.5.15 and 16.2.4 have a cache poisoning vulnerability where an attacker can send a x-nextjs-data header with a normal request to a path returning a redirect. The middleware incorrectly replaces the standard Location header with the internal x-nextjs-redirect header that browsers don't follow, causing the redirect to break. When deployed behind a CDN or reverse proxy that caches 3xx responses without varying on this header, attacker requests poison the cache causing denial of service for subsequent visitors.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 12.2.0, < 15.5.16>= 16.0.0, < 16.2.5CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed Next.js versionExamine the package.json file in your project or run a command to inspect the installed next package version (e.g., npm list next or check node_modules/next/package.json)Affected if The installed version falls within >= 12.2.0, < 15.5.16 or >= 16.0.0, < 16.2.5
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Identify redirect-producing routesReview your application code for any redirects: check getServerSideProps returning redirects, API routes using res.redirect(), middleware using NextResponse.redirect(), or getStaticProps returning redirectsAffected if Your application has routes or pages that return HTTP 3xx redirect responses
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Determine if CDN or reverse proxy caches 3xxExamine your infrastructure configuration to identify if a CDN (e.g., Cloudflare, Akamai, CloudFront) or reverse proxy (e.g., nginx, Vercel) sits in front of the Next.js application and inspect its caching rules for 3xx responsesAffected if A CDN or reverse proxy is configured to cache 3xx responses from your Next.js application
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Check cache vary configuration for x-nextjs-dataInspect the CDN or reverse proxy configuration to see if responses are set to vary on the x-nextjs-data header (or equivalent)Affected if The CDN/reverse proxy caches 3xx responses but does NOT vary on x-nextjs-data header, allowing poisoned cache entries to be served to other visitors
You are affected if your Next.js version is within the vulnerable range AND your application returns redirects AND those redirect responses can be cached by a CDN/reverse proxy that does not vary on the x-nextjs-data header.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped15.5.1616.2.5
Upgrade Next.js to version 15.5.16 or 16.2.5 or later. Additionally, configure CDN/reverse proxies to vary responses on the x-nextjs-data header to prevent cache poisoning.
Next.js 15.5.16 (for v15.x) or 16.2.5 (for v16.x)
- 1. Identify the currently installed Next.js version in your project using `npm list next` or `yarn list next`
- 2. Determine which major version branch you are on (v15 or v16) by checking your package.json
- 3. For Next.js 15.x users: Run `npm install [email protected]` or `yarn add [email protected]` to upgrade to the fixed version
- 4. For Next.js 16.x users: Run `npm install [email protected]` or `yarn add [email protected]` to upgrade to the fixed version
- 5. Verify the upgrade was successful by running `npm list next` and confirming the version matches 15.5.16 or 16.2.5
- 6. Test your application's redirect functionality to ensure normal behavior is restored
- 7. If deployed behind a CDN or reverse proxy, purge any cached redirect responses that may have been poisoned during attacks
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-44572 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-44572 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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