GHSA-36qx-fr4f-26g5
Next.js has a Middleware / Proxy bypass in Pages Router applications using i18n
At a glance
- Published
- Updated
- CVE
- CVE-2026-44573
- CVSS_V3
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Description
### Impact Applications using the Pages Router with `i18n` configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less `/_next/data/<buildId>/<page>.json` requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks. ### Fix The matcher logic was updated to perform the same match as it would on a non-i18n data route. ### Workarounds If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Affected packages
| Package | Versions |
|---|---|
| npm · next | introduced 12.2.0, fixed 15.5.16 |
| npm · next | introduced 16.0.0, fixed 16.2.5 |
References
- https://github.com/vercel/next.js/security/advisories/GHSA-36qx-fr4f-26g5 WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-44573 ADVISORY
- https://github.com/vercel/next.js PACKAGE
- https://github.com/vercel/next.js/releases/tag/v15.5.16 WEB
- https://github.com/vercel/next.js/releases/tag/v16.2.5 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |