CVE-2026-44572 — next
LOWCVE-2026-44572 is a low-severity (CVSS 3.7) CWE-349 vulnerability in next. A fix is available for next — see the affected versions and patch details below.
Next.js: Middleware / Proxy redirects can be cache-poisoned
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44572.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
nextnpmDescription
Impact
Next.js uses the x-nextjs-data request header for internal data requests. On affected versions, an external client could send this 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.
Affected scenarios
This affects applications that:
- use middleware or proxy redirects
- are deployed behind a caching CDN or reverse proxy
- allow 3xx responses on those paths to be cached without differentiating internal data requests from normal requests
Fix
The fix stops trusting x-nextjs-data by itself for middleware redirect handling. A request is now treated as an internal data request only when it is validated as such by internal routing state, preserving legitimate data-request redirect behavior while preventing external header injection from changing normal redirect responses.
Workarounds
Before upgrading, users can reduce risk by:
- configuring the CDN or reverse proxy to vary its cache key on
x-nextjs-datafor affected responses
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | next | ≥ 12.2.0&&< 15.5.16 | 15.5.16npm install next@15.5.16 |
| 📦npm | next | ≥ 16.0.0&&< 16.2.5 | 16.2.5npm install next@16.2.5 |
Affected Products
next.jsvercelDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update next to 15.5.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44572 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
To mitigate this issue, configure any caching Content Delivery Network (CDN) or reverse proxy deployed in front of Next.js applications to either not cache 3xx redirect responses for paths handled by middleware, or to ensure that the cache key for 3xx responses explicitly varies on the `x-nextjs-data` header. This prevents an attacker from poisoning the cache with an unusable redirect response. Consult your CDN or reverse proxy documentation for specific configuration instructions. A service reload or restart of the CDN/reverse proxy may be required for changes to take effect.Source: Red Hat security advisory for CVE-2026-44572 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-44572 in your dependencies?
Find it across npm, including transitive dependencies.