Next.js vulnerable to server-side request forgery in applications using WebSocket upgrades
Impact
Self-hosted applications using the built-in Node.js server can be vulnerable to server-side request forgery through crafted WebSocket upgrade requests. An attacker can cause the server to proxy requests to arbitrary internal or external destinations, which may expose internal services or cloud metadata endpoints. Vercel-hosted deployments are not affected.
Fix
We now apply the same safety checks to WebSocket upgrade handling that already existed for normal HTTP requests, so upgrade requests are only proxied when routing has explicitly marked them as safe external rewrites.
Workarounds
If you cannot upgrade immediately, do not expose the origin server directly to untrusted networks. If WebSocket upgrades are not required, block them at your reverse proxy or load balancer, and restrict origin egress to internal networks and metadata services where possible.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | next | >= 13.4.13, < 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:N/UI:N/S:C/C:H/I:N/A:N- Weakness (CWE)
CWE-918- Platform
- npm
- Package
next- Disclosed
- 11.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-c4j6-fc7j-m34r - 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
-
Next.js vulnerable to server-side request forgery in applications using WebSocket upgrades this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.