CVE-2026-44574
Next.js has a Middleware / Proxy bypass through dynamic route parameter injection
Description
### Impact Applications that rely on middleware to protect dynamic routes can be vulnerable to authorization bypass. In affected deployments, specially crafted query parameters can alter the dynamic route value seen by the page while leaving the visible path unchanged, which can allow protected content to be rendered without passing the expected middleware check. ### Fix We now only honor internal route-parameter normalization in trusted routing flows and ignore externally supplied parameter encodings that should never have been accepted from ordinary requests. ### Workarounds If you cannot upgrade immediately, enforce authorization in route or page logic instead of relying solely on middleware path matching.
How to fix CVE-2026-44574
To remediate CVE-2026-44574, upgrade the affected package to a fixed version below.
- —upgrade to 15.5.16 or later
Is CVE-2026-44574 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 15.4.0, < 15.5.16
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N |