CVE-2026-44575
Next.js has a Middleware / Proxy bypass in App Router applications via segment-prefetch routes
Description
### Impact App Router applications that rely on middleware or proxy-based checks for authorization can allow unauthorized access through transport-specific route variants used for segment prefetching. In affected configurations, specially crafted `.rsc` and segment-prefetch URLs can resolve to the same page without being matched by the intended middleware rule, which can allow protected content to be reached without the expected authorization check. ### Fix We now include App Router transport variants when generating middleware matchers, so middleware protections are applied consistently to those requests as well as to the normal page URL. ### Workarounds If you cannot upgrade immediately, enforce authorization in the underlying route or page logic instead of relying solely on middleware.
How to fix CVE-2026-44575
To remediate CVE-2026-44575, upgrade the affected package to a fixed version below.
- —upgrade to 15.5.16 or later
Is CVE-2026-44575 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 15.2.0, < 15.5.16
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |