Next.js has a Middleware / Proxy bypass through dynamic route parameter injection
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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | next | >= 15.4.0, < 15.5.16, >= 16.0.0, < 16.2.5 | 15.5.16, 16.2.5 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-288- Platform
- npm
- Package
next- Disclosed
- 11.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-492v-c6pp-mqqv - CC BY 4.0
Vulnerability history: next
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 73
- First → latest
- 12.2017 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 5
- High 27
- Medium 32
- Low 9
Disclosures per year
- 2017: 1
- 2018: 2
- 2019: 0
- 2020: 3
- 2021: 3
- 2022: 3
- 2023: 1
- 2024: 6
- 2025: 14
- 2026: 40
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Next.js has a Middleware / Proxy bypass through dynamic route parameter injection this entry
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