CVE-2026-44572
Description
A flaw was found in Next.js. An external client could exploit this vulnerability by sending a x-nextjs-data header on a request to a path handled by middleware that returns a redirect. This action could cause the middleware or proxy to incorrectly process the request as a data request, replacing the standard Location redirect header with an internal x-nextjs-redirect header. If the application is deployed behind a caching Content Delivery Network (CDN) or reverse proxy, a malicious request could poison the cached redirect response, leading to a denial of service for subsequent visitors attempting to access the affected path.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 5.9 | 3.7 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | None | None | None |
| Availability Impact | High | High | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Integrity,Non-Repudiation,Access Control
Technical Impact: Unexpected State; Hide Activities; Bypass Protection Mechanism
An attacker could create HTTP messages to exploit a number of weaknesses including 1) the message can trick the web server to associate a URL with another URL's webpage and caching the contents of the webpage (web cache poisoning attack), 2) the message can be structured to bypass the firewall protection mechanisms and gain unauthorized access to a web application, and 3) the message can invoke a script or a page that returns client credentials (similar to a Cross Site Scripting attack).
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